I think the best book is by Aaron Butler - Success One. It's available in most bookshops that stock textbooks. It contains exact reprint of HSC papers from 2001 to 2004 as well as the Specimen Paper that the Board of Studies released before the course commenced. It also contains a bank of questions by topic.
Another book is released by the Maths Association of NSW and is bright pink. It too contains the past HSC papers, but they are retyped and reformatted. It also contains 6 practice papers. I think these are usually only available through schools but if you're really desperate, you can try your luck at:
http://www.mansw.nsw.edu.au/publications/hsc-solution-books.htm
or hassle your teachers at school.
If all else fails, send me an e-mail and I can send you some practice papers, but I don't have worked solutions, only answers.