For bio I used Nature (which was very good) and Nelson (not so good, but I think one of the examples in one of the exams was mentioned in the book)
By "Nature" do you mean Jacaranda "Nature of Biology"? If so, I agree that it's really good. Haven't used Nelson but as you say, no harm reading it for the case studies.
Oh alright, I have heinemann and am wondering if getting another textbook would be handy. Definitely agree with the different case studies [...]
If you're using Heinemann and you want just one other textbook, go with Jacaranda "Nature of Biology" as NE2000 said. It's huge but awesome.
[...] and I have used Wiki for a bit of help with my holiday homework
Good on you! I'm a Wikiholic.
As far as Web resources go, I can't believe I forgot to mention this:
MIT Open Courseware AP Biology
http://ocw.mit.edu/OcwWeb/hs/biology/biology/index.htmA lot of the concepts in the US' "AP Biology" are in the new VCE syllabus, so I found these videos helpful - especially on meiosis, which I phayled to understand for a while.
Good luck!