How to get A* in A-Level Biology

I'm doing A-level in Biology (Edexcel) and Chemistry (Edexcel)with the new specification. I've seen that there are three exams for each with the last exam looking to seem extremely difficult.
1.)What books/revision guides should I buy to get an A/A* in these subjects?
2.)Are the text books enough to achieve a high grade because I've heard that you have to go beyond the specification in order to achieve a high grade
3.) Do you think it's possible to achieve a high grade by learning/revising from textbook/ revision guides independently?

Read through text-book completely twice (should only take you about 2-3 weeks). Following this you should go through the specification and answer all the objectives - any that you struggle on should be addressed. Finally move onto past papers (in your case there will only be 1-2). Any topics you struggle with should be revised thoroughly.

Buy the recommended text books from teachers (should follow the specification). I would suggest reading the book "how to ace your a-levels". The authors are both doctors and struggled at AS. I employed the techniques they talked about and it was incredibly helpful.

If you have any questions feel free to PM me (A*A*A - Bio, Chem and maths)