Speaking as a born-and-bred Aussie with British citizenship, here's my 2p.
Australia is not for everyone. If you have no compelling reason to go... don't.
Write a list of the things you really want out of life. If you already have them in the UK (or you're already on the way to getting them) then why look elsewhere? Australia won't necessarily change your life for the better; it's not a magic wheel that spins straw into gold.
Like most places, Australia is a land of swings and roundabouts. You have to trade them off against each other. Some things are cheaper—a lot cheaper—than the UK. Other things are more expensive—a lot more expensive—than the UK. Find out what they are, and compare them. Try to estimate their impact on your daily budget.
Research, research, research.
Join an ex-pats forum like this one. Talk to people who've actually made the move and spent at least 3 years in Australia.
Consider your relationships with family and friends. Are you so close that you can't live without each other? Are you fairly independent? Could you cope effectively without your usual support network for months on end? Do you make friends easily, or are you happy to have quality over quantity?
Do you enjoy regular overseas holidays on the continent? Bear in mind that these will be almost unaffordable when you're flying from the southern hemisphere. If you're the sort of person who would miss the benefits of proximity to Europe, think carefully before making a decision.
Above all, don't move to Australia 'just to see what it's like.' If that's your primary motivation, take a holiday and make it a long one.
Australia is an extremely expensive place to live. There is a huge 'Australia tax' on everything that makes Britain look cheap.
Rent and house prices are sky high. High tolls on the major arterial roads, poor public transport, EXTREMELY expensive healthcare, even if you use the government system.
You can still find reasonable house prices if you know where too look, and you'll get more for your money than you do in the UK.
My wife and I think our house is quite reasonable (hell, we've even got
an outdoor spa) and we're not rich people.
Our house in the UK (which we still own) is pretty miserable by comparison.
Yes we pay more for a lot of things, but these days you often can get around it by buying from an overseas online vendor. The value of our dollar is astronomical right now, which makes this an even better option.
But yes, the cost of living in Australia is very high (the wages are too, though I don't think this compensates). It's arguably the most important consideration to make before emigrating.
Toll roads? Well, they do exist (
you can see a list of them here) but only in three states (QLD, NSW, VIC). I think we have a total of 15 toll roads, which is not bad considering this is a country three times the size of Western Europe... Personally I've never paid a toll in my life.
Healthcare in Australia is dirt cheap, particularly since we have a national healthcare service and the government provides a 30% rebate on private health insurance premiums (that's something I missed terribly when I lived in the UK, where I found private health insurance unaffordable).
Australia's Pharmaceutical Benefits Scheme ensures that prescription medication remains easily affordable for low income earners and others who qualify for a subsidy.
For example, I take an anti-inflammatory called Salazopyrin for my ulcerative colitis. Full cost:
$54.80 for a bottle of 100 tablets. I pay:
$5.80. Occasionally I need to use a different medication, called Pentasa. Full cost:
$306.75 for a box of 200 tablets. I pay:
$5.40.
So I have no idea why you would think healthcare in Australia is 'extremely expensive.'