"you get so much more for your money in Australia - better paid job, bigger house etc"
Sorry, I'm laughing out loud at that
Aus is expensive! Don't get me wrong, it's wonderful and has a much better society than the UK, but its days of being cheap are long gone.
Regarding moving - there's no right answer. I have friends (from both Aus and UK) who sold everything, set up in the other country, then years later both the FX rates and house prices had moved in the right direction for them and they returned seriously LOADED!.
On the flip side, I know of other people who did the same and both FX and house prices moved in the wrong direction and they ended their days in a flat in an area you really don't want to live in.
I guess the other dangerous thing is if you sell up you'll be seriously cash rich for a while, so will have to make sure you don't blow it.
The safest approach is to rent your current place out, move, enjoy it, and if you want to return to the UK you have the option.
In short, there are many great reasons to move to Aus, but you don't move here to get rich!