Drop out of sixth form after year 12 and homeschool

I have recently completed linear A Level mock exams and found the whole process really unfair and disheartening, as opposed to the previous AS exams system. However, I am at what would be considered a 'good' sixth form. I study 4 difficult subjects.

The teaching has been really disorganised this year, and I feel as if I can make much more progress by studying independently by myself, as opposed to making the hour-long journey to school, and back again. This year has destroyed my confidence and happiness, and I don't know what another year at school would do.

I know that I would have to switch to an international specification (such as CIE), as I cannot complete practicals outside of school. Is this a problem?

Has anyone else done this before - is it even legally possible? I cannot find any detail online. What happens with predicted grades; and how would I convince my parents that this is the best thing for my education? I really cannot cope with the extra stress that school puts on me for much longer.

Thank you so much in advance.