A-Level Maths. Everything that you need to fill the gap is in there.
As for books (I understand that you are looking for rigourous, yet comprehensive materials), you need to get two different kinds. You will need the A-Level books that are released by the examining board you go with without a doubt. These books are full of questions of varying difficulty, and adhere exactly to the current specification which will give you an idea of what to expect on the exam papers. However, these books are quite bad at actually explaining to you how Mathematics works - for this, you need a more old-fashioned set of textbooks. My recommendation is Pure Mathematics 1 and 2 by Backhouse and Houldsworth. These books are brilliant at teaching you the subject in a plain, but thoughtful fashion and contain some questions that are much harder than those on today's papers. Because of their age, they don't quite cover everything in the modern syllabus - perhaps 90% of it, which is why you need a combination of the two
I used this combination of books and received AA in Maths and Further Maths this year, all done in one year, and this combination of books really helped me along.