Sounds Dull but try working through the past papers without your notes first time.
Then Answer any questions that you couldn't at first by using your notes. If then there are still questions you still can't answer look at the mark schemes and then if your still drawing blanks speak to your tutor and ask them to review it with you
'Mathematics - The Core Course for A Level' is a really good book, as it doesn't assume you've covered certain things at GCSE. I find just doing lots of exercises work- once you're confident that you've nailed the method, then go through as many past papers as possible (be sure to still review your notes every so often though).