There are not a ton of IDEA members from Australia, so far as I can see. If you do not get a better answer from someone who has worked in your part of the world (which I have not, unfortunately) I might suggest you visit the website of either Fitness Australia, or Kinect, if you have not done so yet. They have lots of information about the requirements and process of training. I believe you need a certificate 3 for general fitness, and a certificate 4 for personal training, so you want to make sure the 2 options you are considering offer that.
If you have not done industry research, you might want to look and see if there is a recent fitness industry report for Australia. Those kind of reports tend to have good data on where current growth is in particular industries, and can help when one is starting on a track to point one into areas with good job potential.