Dropping a subject to do it myself

Hello, I haven’t been enjoying my maths classes for a while now, less due to the content and more how it is taught/who it is teaching.

I’m not super intelligent but I think I can teach myself well, I know it is very different but I self-taught myself maths to get me from a 5 to an 8, I understand teaching most of the a level would take a LOT more effort and time, but I think it will be good for me as I haven’t been feeling that great mentally for some time after doing this course.

I trust in myself and my ability to do this if I’m able to, which is what I’m wondering about.

If I dropped the subject the college is teaching me, could I still take the exam with the college/elsewhere and are there any websites with information regarding this?

Thanks!