If you aren't sure about Aus films, your local video rental shop may have an Australian genre section. Rabbit proof fence is one of the top of my head.
I'm in Year 9 and I have done about 2 compositions over my 3 years at high school. I don't know if they are looking for more concepts in Year 12, but my teachers look for examples of concepts in the composition more than if it sounds good. It can't sound all over the place though. Feel confident...