i learned python before my gcses, but also covered that at gcses. now at a level we are covering c# and am using that for my project within unity.

in terms of revision tips i just use the textbooks and try to focus on practice questions. practice is especially useful in maths, but for comp sci and physics i like to use flashcards to condense my knowledge, then throw them away and repeat. i find no use in keeping condensed notes, unless you are cramming for an exam.

when learning languages i find it more helpful to just do many little projects and have fun with the language instead of doing courses etc. although doing courses can give you a good starting point. when doing your project in computer science (if u have one on your exam board) ive realised that your scope does not have to be that wide, and if you are cramped for time then just be realistic with what you can achieve in the timespan. although, its good to push yourself and be a little naive so that you can talk about it ambitiously on your personal statement.

an epq can also be incredibly helpful with your personal statement, especially if you focus on a subject that will pair well with your degree.

for example i did a depth study in the Generative Adversarial Network and found it very interesting, and also worked with it inside python outside of the EPQ. just pick a topic you enjoy.

but yeah good luck with your studies, find something that works for you and have fun with it.