C to an A*???

You will not go from a C to an A*. That's 4 jumps, be more resonable. Most people go down at A2

For my GCSE I achieved 1A*6A2B. For my AS levels, I achieved AAAC in maths, physics, chemistry and further maths respectively. This is really annoying because I want to study Mphys at top university ie Warwick, Birmingham , Manchester etc. I'm scared I wont be predicted an A for further maths, and do you have any advice retaking AS modules alongside A2.Thanks

Does it matter? Uni's care about 3 A-Levels usually.

For my AS is achieved aaac. I am going to take 3 A2s in maths, physics and further maths to study physics. However I'm scared about my C grade in AS further maths because I will be predicted B highest so cant apply to A*AA unis and the work load of retaking AS+A2

Wait, what? You are dropping a subject in which you got an A in for a subject you got a C in? That's one hell of a gamble. Those unis can take you on a physics course without Further Maths surely as long as you have maths + physics as 2/3 of yours A-Levels.

well I haven't decided yet but I find chemistry really boring and I would have to re-learn all the AS stuff as it doesn't count. tbh, I want to do FM to prove myself that C was due to a bad exam day, and I can get A/A* in further maths

My advice would be go with chemistry because you have a significantly higher chance of getting A* in that than FM. If you want an A/A* in FM you would have to retake some FM exams at A2 so that's just more exams for you to do.

While I don't want to give you false optimism, in my own experience I got a C in both my Maths AS core units. At A2 level, I resat both and ended up with an A on the resits and overall. In fact, I cumulatively resat all the core modules, but only in my final exam period did I really decide to 'buckle down' and do my best. So it is certainly possible to drastically improve your grades through resitting, but only if there's a good explanation for your initial poorer grade.

But I think the answer has to be that only you know what you're capable of. Saying "I just didn't work hard enough" was true for me and I ended up being able to do well in four maths exams at the same time when I really tried, but since you did very well in your other courses you perhaps were giving it closer to 100%. And of course, you're trying to do this with further maths, which may well be harder. As has already been said, four grade jumps is a big ask.

Finally, if your grades are top and include maths and other sciences, I think your chances of getting into a red brick university to study maths are still very high. I rarely see further maths as an absolute requirement.

for my AS in FM I got abu. The b was in fp1 and I had a bad day and the U was because well ... D1 and I didn't try for D1 so I got what I deserved tbh . Oh and btw how did you get offers with a C in AS maths (not in a rude way if it sounded a bit rude)? What was your maths predicted grade?