A level self teachingWatch
Could you swap out one subject for something that is just exams (and so much cheaper), like Maths?
The practical component does not affect your grade. You are asked questions about the practicals in the exams so you need to understand them but the actual practicals only affect whether you pass or fail the practical endorsement - you can get an A* and a not classified or an E and a Pass. However, for a lot of university courses, they make passing the practical endorsement a condition of your offer.