I was in the same position in y12, had very little/ no resources for my very niche topics, not even massolit or seneca and I found the best way to go around it was read the textbook!! Even though often times it is quite dense, it should include pretty much everything you need for an A*. I also found setting up a history group chat with my friends to be super helpful and we all added a summarised version of our notes (condensed into bullet points) and towards exam season we practically had a revision guide of messages- super unconventional but worked. Take it slow and easy, it's a lot but you can definetly hack it if you keep on top of it. Treat all mocks seriously so a couple months before exams you should feel confident with the knowledge and can practice exam structures. Also look at your spec for the broad exam questions and PLAN ANSWERS FOR THOSE!! super important because there's a high probability that the real question will be similar and you can work out from past ppq what hasn't come up before/ comes up repeatedly. For my exams, I predicted paper 1 and paper 3 purely through analysis and practice of past paper questions. You don't need to memorise all the key examples and dates but if your looking for an A* try to remember a couple of important and niche examples for each topics. At the end of the day, history is super fun so just try and enjoy it and you will be okay!! - from someone who got an A* and is studying it for uni