Divide your Australian salary by a rate of 2.2 and that will show you roughly the wage / quality of living you'd get if it were back in the UK.....so -
$100,000 = £66,000
But due to the higher cost of living, it's the equivalent of = £46,000
So for that $100,000 you'll get a similar quality of life in Australia as what you would get in the UK on £46,000