I wouldn't spend a fortune getting different school text books. Every school seems to have its own favored books, depending on what exam boards they use. Regarding your PGCE books it might be worth asking if you could see the sugested reading list.
Someone that is very good to read regarding science teaching is Rosalind Driver....she did loads of research on common misconceptions in science....very interesting and very useful.
Three general books that I found useful are the ASE teaching secondary Chemistry, Biology and physics series (three different books)
Don't worry about your science being 'out of date', you will get up to speed, so fast. This was something I worried about, but you will have no problem.
I'd keep poping into schools to get experience.
Good sites would be the national curriculum website....will give you a good idea of what is taught and when.
Useful sites, bbc bitesize, most of the major museums have good stuff.have a google, you'll find loads of stuff.
Also (with a caveat that some of the people are very rude and/or barking mad) it is worth popping into the Times Education website. They have a section for prospective students, PGCE students NQTs and a science area. The Opinion site is wild on times!