You can download the Core Science course specification if you click here - AQA Core Science Specification.
Rebecca: You can go straight to the page where you can get BTEC past papers if you click here.
Remember you're doing Unit 8. Start with March 2014 (before this there wasn't a unit 8), and work forwards. The most recent ones need a teacher login, but older papers like March 2014 are available to everyone.