Isaac Science

Hello, I am aiming to do a lot of the Isaac science questions mainly physics and maths Cl 2 and 3 questions I am currently on 20 questions(I know its very low) and aiming to finnish 200-300 before the end of the christmas break but I was just wondering did any of you self learn a lot of physics and maths topics to be able to do a lot of the questions because that is were my problem is my school hasn't done a lot of the spec for maths and physics so it is kind of restricting me also if you did self learn them what resources did you use and like how long did you spend. Thank you!!