To WannabMavrick
I was in the same situation after i left highschool, i went through i school in perth call SIDE (School of isolated and distance education), they send there work through the mail and you complete the subject through correspondence, they offer it Australian wide to. It took me a year to complete and now i off to flight screening so the courses they offer can be used for ADF. I do know there is a course offered in Queensland which would probably be better for you but i think its expensive. if ya need there number just let us know.
Regards Dan