jazzop,
don't just consider all the major one's. If you flip the yellow pages, you'll find a whole bunch of small business and ambulance operators. Turnover there is usually quite high (due to the fact that trained staff is moving on), but you might be able to secure a sound basis for your future endeavours at one of the majors.
Biz operators also offer the chance that you get the 'big picture' about the entire operation.
If I remember correctly I overlooked some job adds in the DownUnder Forum, so I'd suggest to start from there....
Cheers
fcit