I have been in the UK for around 18 months, and this is just my second trip to Australia in that time. For what its worth, here are some comparisons between the two:-
Australia is expensive. Beer in our local, the Royal Oak in Clifton is GBP3.30 a pint, and that is expensive for the UK, its much cheaper in parts of Manchester. In many pubs in Melbourne its A$10-12 a pint, and at the current forex rate that is GBP7-8. Ouch. The hi A$ skews the numbers a little, but things are expensive here. But people earn more also
Traffic is getting worse in Oz.....but it has a long way to go to get to the UK levels of congestion.
UK drivers are more considerate than Auzzies - I guess they have to be, as there are more of them on the roads. Poms are much better with cyclists, and Auzzies on a main road are far less likely to let people turn Right, in front of them onto a side road.
The UK is a little bigger than Victoria, the most densely populated state in Australia, with 5.5m people. The UK has 62.2m people, ie it is 11x more populated for the same land mass. This state tells us a great deal about liveability in both countries.
The roads in Australia are much better than the UK. There have been lots of pot holes this year due to the high rainfall, but many have been fixed, in Australia. Poms will know this is not the case over the Old Blighty.
I just bought the same car on each country - lets see how they last. Did a wheel bearing in the UK, I reckon the wear and tear in Australia will be much less.
Hay fever has been shocking this Spring in Oz, much worse than the UK. I never normally have a problem in the old country, but my eyes have been streaming here in Oz.