i assume (as it's provided by USyd) that the university library being spoken of is the Fisher Library.
No, it doesn't really have HSC resources (ie. textbooks, studyguides) as such, you would be better off going to your school or local library for those materials.
What uni libraries offer though, is access to weighty academic works, and this is really helpful for research purposes. Ie. English Extension 2, History Extension, Society and Culture etc...
There are many books held at uni libraries not widely available either because it is a very specialised text on an obscure topic, or because it is out of general circulation.
In general, unless you're taking the above subjects (or a humanities subject requiring research) then i can't see a real need for access to a university library like Fisher or Macquarie.