It really depends on the topic area of your Major Work to which Library is most suitable.
State library is definitely one to check out. GREAT resources there! However, I have also heard that both Macquarie University and the University of Wollongong provide access to their resources for HSC History Extension students. For my preliminary research my local libraries and my school library have both sufficed, so don’t forget to check out your own local and school library!
Macquarie uni library is excellent if you are working in ancient history (I say ancient as I have no clue about modern history resources). I signed up with the HSC History Extension associate thing and made ample use of it.
state library is an absolute must. i pretty much lived there throughout the year while i was doing my major works. so many great books from across the time, not just recent ones, which is great for showing changing historical perspectives over time.
- State Library (open to public, can't borrow though)
- Macquarie Uni (Hist-ext friendly, can borrow for $25 fee)
- University of Sydney (Can walk in, good collection, but do not recommend borrowing from)
Start with your school/local libraries though. You'll be suprised what you can find.