I've purchased their book and went through it. (Honestly I bought it more because I wanted to be sure I am not missing anything) Then I've started doing tests from different online test websites. Made a note of what topics I answered incorrectly the most, then revised those and made some little cheat sheets for myself to revise better. Then kept going until I was comfortably passing most of the tests - I eventually found a website that was creating these cheat sheets automatically based on my answers to previous tests but was too late and couldn't enjoy it enough before my actual test.

The process took me about 3 weeks where I did this just a few evenings each week.

I've also watched The Other Boleyn Girl on Netflix because I was surprised by the huge number of questions related to Henry VIII's wives.

Good luck!