As has been mentioned, you'll have to convert any trade qualifications over to OZ equivalents at your cost, so just double-check that first. Secondly, start doing your homework NOW if you're considering moving there, the more prepped you are, the better you'll understand if you can afford the move (check wages, rental and house prices, food at online supermarkets, utility bills etc). Third, (and more homework), read and ensure you understand migration and what's required for being accepted, and check your points to assess your eligibility. It's a confusing, long and complicated process, so just be sure you know what you want (you can be sponsored for a visa, you can get a temp work visa etc etc etc). Also make sure you understand the implications of NOT having work, as you could get booted out if things don't go your way. And finally, don't be suprised if no-one wants to offer you a job whilst you're on the other side of the world. It's easy to say you'll come, but getting on the plane is a different story...
As for OZ itself, at the moment, it's more expensive than living in the UK/Eire due to the shite exchange rate, so visiting as a tourist is expensive (as is living off savings 'back home'). That said, when you start earning an OZ wage, it's all relative, so you won't notice too much difference. As has already been said, the West coast is the more prosperous area of OZ, and the wages are higher due to the vast mineral reserves and subsequent businesses out there. The East coast is also prosperous, but more for tourism. Sydney's horrendously expensive, as you would expect London to be. It's a great place, been there three times now, and it always challenges your mind as to why you live in cold, wet Europe.
Having travelled extensively, it's only when you go somewhere else that you realise the grass is no longer greener back home. You're only young once, don't waste it by just staying put, there's too much out there to see.
^ And LOL at the Kiwi answer above!!! Go the AB's eh?