The four Cs I got in GCSE were in English, Maths, and Double Science. My other GCSEs are Ds and Es. Those are my only formal qualifications so I have no other grades to speak of.
I'm currently not attending any classes whatsoever. The only thing I've done is enter myself for the Maths and Further Maths A Level exams at my secondary school. As such, I'm responsible for my own maths education, and since I don't want to waste money on a tutor, I've been teaching myself entirely off the internet. It's one of the downsides to this approach, and I've run into several issues going down this route.
The first issue was one of motivation. There is no one breathing down my neck to get anything done, there are no classes to attend and passively absorb knowledge from, and there are no deadlines to meet except for the exam dates, which seem quite far and distant. So it's extremely easy to procrastinate and fall behind schedule. It was for that reason that I had to downgrade to AS Further Maths. Luckily, I managed to get my act together in January and have been studying relatively on schedule since.
The second issue is one of no teachers. My goal with doing A Levels is not to pass the exams, but to learn maths for the sake of learning and mastering it to the extent that A* grades naturally follow. However, the Edexcel specification is more focused on making sure you can do the maths rather than understanding it -- especially in calculus -- so I've found it extremely frustrating at times. With no teachers to have explain concepts and proofs to me, I have to turn to the internet and try and figure everything out myself.
The next academic year, after my maths is done and over with, I'll be attending an independent centre where they provide tuition for fast-track A Levels as well as entering you for the exams. I have no choice in this matter since English and the sciences have a graded coursework and practical component which must be submitted to the exam board through a registered centre.