Even though you didn't finish the course, getting the same level of knowledge and skill as you have now would take some effort in the civil world. Even though the PC-9 is a crap platform for preparing you for the RAAF's real aircraft, it's still a much better platform for learning IF than a 30 year old duchess. Plus I can't imagine how I would have gone trying to gather the knowledge in the civil industry that the RAAF rammed into my head during groundschool.
If you stay in it might help you get the cash together, but if you are the kind of person who works hard at the work they are given, you might find it hard to get the time and continuity to learn your flying at any reasonable pace. A lot depends on what job they give you. As others have said, if you can get a desert deployment, come home with a bunch of cash in the bank, resign and 6 months later you are in your first GA job with all your basic quals done. That's IF you get the right job in the RAAF.
If you want to fly, get on with it now. You will hurt financially for about 4 years while you get the time together (this doesn't have to be the end of the world, especially if you are single) and you may even have a great time. By the time your RAAF buddies finish ROSO, you'll be a Jetstar Captain earning $40k a year more than them.