Currently live in Adelaide which is significantly nicer than Preston. The city has everything I could ask for and is much cheaper than many of the other major cities in Aus.
$10 a pint in Perth, more like $5.50 in Adelaide. The wine regions (many of these in SA) are a great way to spend the day. Also the beaches are clean and not covered in dog eggs etc. Nothing better than riding home from work then down the beach for a walk watching the sunset. The local hills are full of great trails that are dry for 9 months of the year!
Cost of living is ok. Yes both food and rent are more but the trade off for me is that I get paid two an half times more than I could get in the UK. My cost of living is nowhere near twice as much.
As previously mentioned you need to way up what you want from it. I saw no real future for me in the UK, I'd be working hard for very little reward and when we had an oppertunity to move to Aus (perminant residancy via the wifes job) it was a no brainer. We are now saving to buy a house and still have plenty of disposable cash left of to enjoy life, which we do.
As for Aus being backwards in regard to rasism I don't think it is any worse than the UK. In fact I think the Aussies are far more tolerent than in the UK well the ones I work with are. If I hear it I'll challenge it. 99% of people here are migrants of some sort so people get along. I've yet to hear the very common UK phrase "I'm not racist but".... maybe the Aussies are just more open about opinion, rightly or wrongly" it's no different. Yet a big thing that many seem to forget... It's not the UK so stop expecting it to be. Things are different some you will like some you won't.
I've yet to really miss anything from the UK. Family is an obvious one as are friends but skype and email do a good job in bridging the gap left. You'll make new friends and adapt to life here. I'm much happier overall as I can see a genuine future for myself and not simply going through the motions of life. I say take the chance whilst you can. I know if I didn't a few years down the line I'd be kicking myself.
Also spiders aren't everywhere. You can swim in the sea and not get eaten (most of the time) Snakes are about too, makes bike riding that bit more "rad" snakes sunning themselves look just like sticks!
Just my 2p worth! but good luck either way.