Well I didn't like the A-Level books I looked at. They just all looked rubbish to me. Too much waffle and decoration. Then I found the Exam Solutions website. I generally like the no frills approach. The other option is the Khan Academy (again online videos).
Perhaps someone else knows a good textbook for High School level?
This OpenStax textbook claims to be a connection for AP courses.
Khan Academy is good as a first pass to the subject, but difficult to search for something specific that one might be looking for.