Note: The syllabus for this paper changed in 2019 (see the official website for more details). Previously I made a playlist of past paper questions by topic. You can view it below, but some of the topics are no longer in the syllabus.
Similarly, past papers and markschemes for the paper can be downloaded below, but these are for the old syllabus:
Buy the official course textbook, exam practice questions and revision guide (for the new syllabus) here: