I spent 15 years in Oz, where I met my DH, and had my DSs. We came ('back', for me, as I lived in the UK til I was 25) to the UK 9 years ago. DSs are now 11 and 13.
Like others have said, be careful! It's not like the programmes would have you believe!
Yes, the weather is generally a fair bit better; of course it is.. BUT if you live in an unheated house in Victoria, those southerly winds come straight off the Antarctic in July. Brr. In summer, the pavements melt! In the tropical north the humidity flattens you (and you can't leap in the sea to cool down- sharks, crocs and box jelly-fish!) if the rain doesn't wash you away! You have to keep young DC under cover from 10 to 4 every day as the sun is so fierce- and it gets dark by 6.30pm!
The Australian economy is booming, on paper, but there is a strong feeling of '2 tier' wealth: those with an interest in the mining industry boom; those who haven't. It is entirely dependent of the Chinese economy continuing to grow at breakneck speed.
For me, though, the 'biggie' was, tbh, the people. Aussies are a bit larger than life. They can be fabulously back-slapping and gregarious, but you have to be ready to grit your teeth when, 2 stubbies in, they're berating the Bloody Abos or Pakis, whilst calling for their sheila to fetch them another can. They're, outside of the major cities, rather suspicious of academe (and 'outsiders' tbh!). To me it's so typical that every 'Move Down Unda' show states the 'fact' that the 'education system is second to none', but it's just a classic Australian assumption: it's Australian so it's bound to be the best, innit? In fact, of the 4 families I know who went over (and all came back in the end), all had DC who had to be given help to catch back up with their peers back in the UK. Sport is revered far above Physics and Maths (in some schools, being good at that is considered 'gay'); religion is a Bigger Deal, even in your choice of career. Where we lived on the Sunshine Coast we had the choice of 6 private schools, all of which were run by religious foundations- 2 were even Fundamentalist, fossils-are-the-work-of-the-devil stylee.
Our neighbours on the Coast were nice enough people but blimey, what a monoculture! Every bloke spent his time off, fishing, every woman down at the shopping Plaza, everyone got to together for barbies and many were borderline alcoholics. You'd find way more culture in a city but maybe not with young DC, living in suburbia. And houses are expensive! An affordable good sized family home would be out in the stick with rainwater to drink and a septic tank.
Swimming pools are great! But you have to look after them all year round, even for the 6 months you're not using it.
An interesting observation: I worked in a state hospital where there were many ex-Poms, many who'd been in Oz for decades. You could divide them into those who wish they were able to return to the UK but were sort of trapped by effectively having Aussie kids in education or married, with the grandkids; and those who'd never go back to that old 'shit hole' (sorry, but that's what many would say!). How would you divide them? Doctors, nurses and professionals in the first camp; tradesmen, porters and cleaners in the second.
The wildlife would probably be the least of your worries 
and, actually, Huntsmen are a good thing as they clear any redbacks out of the house! A dog is handy for de-snaking the garden, too.
By all means go but don't sell your UK house.