I'm Australian and have divided most of my life between there and the UK. I advise against it.
You've got to consider not just "Australia" but the specific region. If it were Sydney or Melbourne, maybe. Those places have changed hugely since I grew up and now just as interesting, cultured and diverse as London, Brighton or Manchester. I don't know Brisbane but northern Queensland is much less so. You might experience considerable culture shock in your interactions with people there.
It does have some astonishing natural scenery but beyond seeing that as a tourist, is it enough for a life?
And it's hot. REALLY hot. There was a time when this might have been a selling point - think picture postcards of muscular tanned bodies on sandy beaches and endless reruns of "Neighbours". Now, with global warming taking off and much of Australia's hottest regions literally catching on fire every few years, not so much.
Doing it to "see how it goes" sounds like creating trouble to me. Yes, you could do that as a single person, but as a family: what happens if after a few years two of you find it an idylic paradise that you refuse to be dragged away from, while the other two are bored silly and crying into your pillows with homesickness every night? And it's not like you can just jump on a plane to go back and forth for a weekend whenever you feel the need.
Finally as a pp said, housing in Oz is ridiculously expensive. Time was when anyone coming to the UK from there couldn't believe how expensive the UK was. Now it's the other way around. You'd have to do the sums for your own situation but there are few people I can imagine coming from another country and buying into the Aussie housing market.
I think you'd need to all visit the specific place for at least a month and properly get to know it, before taking such a leap. Short of doing that and deciding you're all smitten, I'm just not seeing the upside.