I disagree with those who say to come out on a trial to see what it is like.
We have been over in Australia for coming up 3 years. We initially moved to central qld. Loved it, but could never see it as being 'home'.
We considered moving back to the uk, then decided to try out Adelaide. We have been here for over a year and love it. So glad that we decided to on here rather than return to the uk.
The point that I want to to make is that if you come out then be prepared that you might not like the place that you first land, you might need to go through a couple of jobs before getting the right job. Be prepared that initially you might need to take a lower job, take the lower job and then prove that you can do the higher job.
If you think of it as being a trial for a few months, then odds on you will return back to the uk, as it is the first few months that can be the hardest and most stressful.