Most importantly for this I recommend having a chat with your teachers to see if there are specific books or calculators they want you to use as they teach you - you don’t want to buy twice!
However, here is a guide to my favourite resources for A-level Maths students!
Don’t under-estimate the importance of GCSE Maths - they taught it to you for a reason! Yeah sure their are some bits which you will feel are less important as you progress through A-level but there will be some topics that you really can’t get away from!
Here I will explain the topics I think you really need to review before starting A-level, or at least in the early days. Becoming fluent in these topics is absolutely critical to you picking up the new topics of A-level. This is because every new topic will use these without teaching them - your knowledge becomes expected and that is what gets tricky!
Below the video you will see a summary of the keys points which you can and a downloadable version too in case you would like to use it to support your studies.
You will find module 0 jammed packed full of revision of the month goes on so check it out and use it to help you revise these keys concepts!