I don't think schools typically offer for you to be accelerated in a subject. Probably because they don't want the hassle of organising everything and then having to keep track of you. It's really something you have to push for. If you can do well in an accelerated subject, it'll be an awesome advantage to have in Year 12. This should be made obvious to everyone, but acceleration isn't something that my school promotes or advertises at all. Funny, that.
If I had any foresight I'd definitely be doing the HSC for one of my subjects this year.