Jimmy.
I did just what you're contemplating though I had no intention of returning to Europe (but did). I've dual citizenship so could stay as long as I liked. If you can only get a limited visa you may be better off staying in the UK.
Lots and lots of people who get their Australian CPL/ATPL never actually get a job. It's a tough industry. I was lucky and gained a leg up courtesy of one of the few true gentlemen in aviation (thanks Chesty).
If you get a job you'll see and do things you'd never get elsewhere in the world but it'll be a long hard slog. You'll then have to face converting your licence when you come back to the UK.
Getting your licence and hours in Europe will see you with a better chance of that elusive airline job. On the other hand if you go to Oz you'll never forget it.
Drop me a line if you like.