It's not too competitive, there are less than 50 in the course and there's generally a few drop outs (the 1st year timetable is rediculous)
You need physics are a pre-req (year 12 or uni), and biology/anatomy does help.
There's a lot of non-year 12 people doing the course with, so there's a good chance you will get in.
Even if you don't get in for 2009, you can talk to the course covener about doing rad subjects in your science degree (one student did that and passed, then was able to switch the following year)