You need to consider your living budget and plan your prospective trip accordingly . Living on the beaches in Sydney will be very expensive.
I live near Manly on the Northern Beaches and house price, rent/buy , is completely mad, I could buy a French Chateau near my native Monaco. This is one of the many sites you can have a look at for house prices www.domain.com.au
Given what you describe as the lifestyle you are after , I would suggest you look at Gold Coast (the city) , so much cheaper, no traffic, easy lifestyle.
In the Sydney area, look at maybe Maroubra for more affordable suburb.

Several families I know have left Sydney to move to the Central coast and commute by train. So Avoca, Copacabana, ....

If you want to have a feel of Sydney life, you should look a the suburbs you can afford and stay there and try to see how doable "beach life " is from there. There are no trains to the Northern Beaches , only bus or ferry if you go to manly , you would have to take train+ bus to the Bondi area. Unless you live on the beaches as I do, you won't be doing much beach life during the week , because it is a big city and you don't walk down for a swim after work as you would have to travel for quite a long time.

End of year equals to the Australian long summer holidays and it will be hard to find accomodation if you don't plan it in advance. Everything will fill up pretty quickly.

Holiday wise, I find Noosa and Byron Bay really lovely, probably because they have a European feeling. Water will be warmer as well.
In the south, Jervis bay is nice, but it will be packed at Christmas. Still lovely and great beaches.

As someone from the Mediterranean , I am always amazed at how people seeking the beach life plans on moving to the other part of the world, cruelly far from family and friends, without considering that you have as much if not more beach life in Spain, Greece, Italy, ... You can buy a massive mansion for what you would pay for an average house here. I know you now need a visa for the EU, but so do you for Australia. Water is freezing in Sydney, and we have had two years of very very wet summer.

There are plenty of reason why people move to Australia, but if it is just for the beach, you can make better choices.

There are several discussions on people leaving Australia

Personally , I can't wait for my DH's posting to be over.
Flight prices have skyrocketed as well. Everything is so stupidly expensive,
By all means, come for a holiday at the end of the year, Australia is a lovely country with beautiful landscape, but maybe in June or July, go to Sardinia, Santorini, Mallorca, Menton, ... so you have something to compare it with.

If you need a big city for jobs, Barcelona allows you to do beach life from March till November and between November and March you go skiing at La Molina less than 2 hours form Barcelona. You can live in Gava or Castelldefels in a flat or house right on the beach , 20 min commute by train

I live on the central coast. We love it here. www.icentralcoast.com/central-coast-beaches.html

Look for accommodation on the Sunshine Coast when you visit Australia Zoo. That will cover the stay in a beach town as well. As a PP says the time you are looking at visiting is our peak tourism period and it will be busy.

Unless you are extremely cashed up and earning a huge salary, the lifestyle you want in Sydney is not feasible. The Gold Coast is still feasible but depending on your workskills, there could be a long commute if you need to work in Brisbane. The Gold Coast is very different to Sydney though.

I second PPs' warnings about Sydney. Property is breathtakingly expensive, even in suburbs far from the beaches. Also, with lots of people switching to WFH during the pandemic there has been a flow of Sydney money to the more attractive regional towns such as Coffs Harbour, and prices have risen accordingly.

What sort of work do you do? Is it something you could do in a coastal town? If you're keen on NSW you could look at Bateman's Bay and Merimbula (south coast), Tweed Heads and Brunswick Heads (north coast) or beach towns commutable by train to Sydney, such as Terrigal, Coledale and Austinmer. The Wollongong area has some lovely beaches.

But be prepared for gobsmacking prices wherever you go along the coast. Have your holiday first and see if you can stand the expense of actually living here.

We lived in Sydney and loved it. Life was expensive but so much more affordable than the uk (in our jobs the salaries are much better). Espeacially with young kids because you can spend so much time outside. We lived in a suburb - lilyfield - which was a lovely inner city suburb. It was about 30-45 minutes by car to get a choice of beaches and that suited us.

Absolutely loved it. Perfect place for kids and a family. Miss it so much it hurts sometimes.

It is hard to recommend a beachside town. We visited a few, but I never particulary liked them. They were all fairly similar with no character. I liked the beautiful and (relatively) older inner city suburbs. It's hard to find a seaside town with that feeling.

For a holiday destination, Jervis bay absolutely worth a visit. Loved it so much. Beautiful beaches, calm sea and the closest I’ve ever been to dolphins in the wild.

We lived in Sydney for a year some time ago. We lived in Balmain which we loved. No beach life but could get the ferry to work or a short bus ride. Adored the life style too, so much outdoors time.

If you are staying in curating I’d look at doing day trips to areas on the coast south of there. So towns like Merimbula, Eden and Bega.
I would stay at noosa when you go to queensland. There are buses from there that go to Australia zoo. Look at Maroochydore airport which is the closest and should have direct flights from Sydney. Accommodation at noosa river is a bit cheaper than noosa itself and it is only 5 minutes away. If you go for longer than a weekend consider driving north to Hervey Bay and either going to the Great Barrier Reef at lady Elliot island or Fraser Island which is the largest sand island in the world. Both easily accessible from Hervey Bay.
For your 3 nights in Sydney I would stay at Bondi for one lot. And Paddington/Potts point for the other. Rent a house through air Bnb. Both are extremely pricy areas to live but great to see the best of Sydney.

Seaside towns north of Sydney that you might consider are Newcastle (more of a city but I think it’s great) and port Macquarie.

I wouldn't come to QLD just for Australia zoo. It's vastly overrated. Taronga Western Plains (Dubbo) is much better imo & the (5 hr) drive from Sydney will give you an impression of what the 90% of Australia outside the eastern coastal strip is like. It's pretty amazing. You could loop back around to the central coast & do the stunning drive back to Sydney, stopping at towns & beaches along the way & maybe find somewhere you love.

I'm a QLD'er is it stunning. But explore further than sunny or Goldie. It's true beauty is in finding the places/beaches off the beaten tourist path where you have a beach to yourself & the national parks.

Close to Currarong is a good place to look at beachside towns. If you're visiting your relatives, on the way down, you'll pass through bigger towns that happen to be close to the water - ie, Wollongong, Nowra etc - these are the places most people live - most parts are not beautiful but it's affordable and close to services. Further south is Bateman's Bay, Ulladulla, Mollymook etc.

On the opposite side of the bay from Currarong, are Huskisson, Vincentia (almost the same place) and Hyams Beach. Hyams apparently has the whitest sand in the world - not sure if that's actually true or not, but it is very lovely. Around Sussex Inlet (near Huskisson etc) are more 'normal' towns - not very appealing looking but slightly more affordable. Take a drive around and see the lay of the land.

All of these places will be very busy in December - be warned - and accommodation will be difficult to get and $$$$$ in all respects (accommodation as well as eating out).

Hi, I am based in Qld. I would spend a few days in a nice hotel in the Gold coast and visit the beaches there. The Gold coast has a great vibe. Then book a night in Brisbane CBD and visit the Brisbane City beach. Your son will love it. Have a trip up and down the river on the free city cat boats.

From there head up the Sunshine coast via Australia zoo (I agree Taronga zoo in Sydney is better). Day trip at Australia zoo and book the hotel at Mooloolaba. Spend a couple of days at Mooloolaba. Again the beach is lovely there. Solar vibe to Noosa but a bit closer. If you decide to stay longer on the Gold coast go to Currumbin wildlife as it's better for koala cuddling than Australia zoo. (Just my opinion).

Have fun. We came over 7 years ago having never even visited! And love it here

Regarding the flight, I'd recommend buying a seat if you can afford it for your DS. That flight is going to be pretty brutal with a 20 month old. I'd also break it up with one night somewhere each way or a long layover so you can use a transit hotel (e.g. on Doha Airport you can rent the hotel in the daytime and it has a swimming pool). Don't plan too much for the first couple of days when you'll need to catch up your sleep and adjust to the time zone. I've done the flight many times with young children but I've been able to hand the kids over to my parents and go and nap as needed.

Have you explored visa options? It's damn hard to get into Aussie to live and work. Also agree with people re the difference between living and visiting.

Sydney can be a bit concrete surburbia unless you are by the beaches but the beaches are an arse to get to on public transport from the CBD (eg Bondi is a train and then a packed out single decker bus... summer weekends means you often have to wait for over an hour just to squeeze on that bus with all the beach goers) and prohibitively expensive for property.

Sydney I actually found very dull behind the tits and teeth of circular quay. Plus it rains too much (50% more rain than London!) which I never expected until I lived there and holy shit when it rains it pours down. Often for days.

Melbourne however has a much grittier, European feel. Much less of a tourist city.

Brisbane was an unexpected delight. I was told it's basically 'Brisvegas' but we loved it.
Re NSW, Jervis bay where your family are is lovely. Hunter valley is worth a trip as is the Blue Mountains. Noosa also.

The seat thing is because he is under 2, he can travel free on your lap. But its not fun travelling for 20+ hours with a toddler on your lap. To get a seat you need to buy a third ticket. Also make sure you request a child's meal specifically or they will just allocate a normal adult meal. With a journey like this, I'd always recommend booking through a travel agent to ensure points like this are covered (they will normally price match with online prices).

Also just to point out, a child ticket is cheaper than an adult ticket.

Thinking about flights though. With covid I expect they won't seat anyone next to you anyway so when you select seats book your partner and yourself with a blank seat between you and it will probably stay empty then you can use the seat for free. Just an idea

Fair enough suggesting Europe etc, but Australia is probably attractive because of the language? Op probably speaks English and not Spanish?

Depends what you think of as the Australian lifestyle - but I’d go to Adelaide for a week. It’s cheaper. Much easier to get around. Great beaches and the hills. And you could then go up to the flinders rangers to see the outback.

I would def go to Adelaide for the weekend and. It Australia zoo if you want to properly experience an Australian lifestyle

Oh if you do go to the outback go on a tour and do t just drive there in your own!!

@Movingonup22 Adelaide is amazing , I love it, prefer it a thousand times to Melbourne. However if someone is after a beach life, water temperature is a big factor and OMG, ice bath, except for maybe a month a year, when it is a cool bath.
No wonder expedition to Antartica leave form Adelaide, they are just in front of it and polar winds often hits it!

@dipdye Malta, Gibraltar, and further away but not as far as Australia, Barbados, Jamaica, ...where English is spoken and believe me you'd get a far greater beach life in Bahamas, piking up conch shells from the beach and swimming in calm warm waters than in most Australian beaches. My house is walking distance to the beach, but the Pacific Ocean is not that pleasant if you are not a surfer. Half of the year it is freezing, the other half is is very rough. I go to the beach with my chair and book, and will go for a dip but you don't really go for long swims, you will be hammered by the waves, have to go behind the waves and surfers line and I can't help thinking about sharks when I am there. The "swim between the flags" recommendations is ridiculous because you can't "swim" , you can jump, ride a wave, hoping not to be hit by a wall of bodyboarders coming at you at full speed, but swim, as in breaststroke , free style or even backstroke, no way. It should be "enter" the water between flags.

I swim more when we go to New Caledonia . Not that this has happened a lot with the border closure to exit the country.

A language barrier isn't such a big one. It takes months if not years to get an Australian visa and it is quite $$$$ as in thousands of $ for each individual visa. Learning Spanish is cheaper and quicker.

Australia is expensive. Like really expensive. The price of fruit and veg is ridiculous compared for what you get in the Mediterranean . in Aldi, this week $1.29 for 1 (one and not even very big ) lemon. I get a kilo of lemons for the same price in any market, Crap food is very cheap on the other hand.
A lot of Australians do not have a lot of savings allowing them to travel and discover the world, or even go to cultural events.

Australia is beautiful, but you can get more for your bucks elsewhere, in equally beautiful places if your only goal is beach life .

Last but not least , I strongly recommend against touring the outback by car on your own with a 20 month baby on board. It is not exactly a motorway with smooth asphalted roads with petrol stations every 50 km. If you have car trouble, you are in big trouble unless you have a satellite phone.