As long as you have plenty of money behind you or a stable job to go to (which obviously you have with DH company) then I would give it a go.
We lived in Melbourne years ago when the pound was strong and rented in South Yarra which is a really nice area near the CBD where all the main offices and businesses are situated. There are LOADS of parks, coffee shops, boutiques and amazingly beautiful places in and around Melbourne city centre.
I don't have any experience of the school system but it is more expensive to send kids to school over there are you pay for everything. There are plenty of state and private schools. I second the advice to go and post lots of quesitons on the British Expats site.
I love Melbourne and would move there in a second. We have our visa's but it is just that we don't really have enough money behind us to go yet and no job to go to yet as OH is in construction which has slowed down a lot over the last couple of years over there.
The main things we found that were actually bad points that might put you off are that you do get really, really homesick. Even though English is the main language, the dialects and colloquialisms (sp??) mean that they don't always understand what you say and you don't understand them at first (mainly they don't understand you at first). It is very very far away. This may be obvious but although it is much quicker to get to and fro between UK and Oz, it is expensive and still at least a day away. Sometimes when you are homesick and just want a friendly voice from home, you pick up the phone and realise "Oh, can't just phone home cos it is 3am there just now" and you have to wait. That was the real bug bear for us. Just ride it out though. For most, the homesickness passes. They pay a lot more tax, there are cost issues they don't mention when you go to buy a house (also involved with tax) but I am not sure of the ins and outs since we rented.
However, get Skype and make sure you have lots of family video conferencing to keep in touch and actually get to see your friends and relatives back here and they can see you via Skype (or whatever package). Really helps.
Also, Melbourne is a vast city and has many, many suburbs. British Expats site is great for info on this kind of thing and especially info on schools etc.
I have heard of a lot of people who went to Oz, tried it for a while, got homesick and came home only to realise everything back here is exactly the same as when you left. Apart from everyone else has got on with their lives and are (mostly) not sitting around waiting for you to come home.
It is obviously entirely up to you. We could go in your place if ur DH doesn't take the opportunity - pass our details on to his company LOL. It has taken us a year to get our visa and will prob b next year before we can even think about actually heading over. We just want to go now!!!
I am terrified to tell my dear old Dad about it all tho. That is the hardest part for me....
Best of luck.