Ruth,
They don't advertise it this way, but if you think of it like this it may help you understand where you are at (from the organisations perspective)
ASA consider that you have essentially applied to go to college for a year and study for a Tertiary qualification. Like any Tertiary courses it has entry requirements, and because the ATC course (Dip.Av.) is both vocational and federally regulated it has a medical as well as an aptitude/educational entry standard. They will meet your costs but they don't consider it their responsibility to organise anything.
ASA is not the ADF. You haven't been given a job so much as been given an opportunity to train for which you will get paid. After you pass the theoretical and practical competencies required to satisfy both the Diploma and Licensing regulations you will be offered permanent employment.
The course is hard...4-5/10 smart, fit people with aptitude either fail or withdraw. A lot of self motivation is required to get you through it because you WILL face personal challenges that will have you asking yourself what the hell you are doing there. Trainees draw that motivation from various places; love of aviation, the money, the uniqueness of the environment... whatever it is, if you don't have enough of it you will not succeed. ATC is a responsible job, you CAN kill people if you have a bad day...possibly a whole lot of them. Ask yourself if you have that motivation now, because if you don't you may as well stay at home.