For A-Level Maths you have 6 books (3 AS level and 3 A2 level)
C1 (Core Maths 1) the easiest book and simple algebra and polynomials (non-calculator paper) 1h30min long
C2 (Core Maths 2) continuation of C1 and goes more into depth (geometric series, differentiation and integration) 1h30min long
S1 (Statistics 1) or D1 (Decision Maths 1): I did S1 because my school decided it and includes probability and variables. 1h30min long
C3 (Core Maths 3): First book from A2 level and goes into complex calculus and trigonometry and geometry. 1h30min long.
C4 (Core Maths 4): The hardest one of all, really complex Integration and use of partial fractions. 1h30min long.
M1 (Mechanics 1): This can vary depending on the school and can be replaced by S1 to the final year but I did this in the final year and It's all about projectile motion, moments, vectors (pure physics). 1h30min long