If you get AAAc, and achieve it, you can apply to a fair few med schools, although some want AAAb, so it may be worth resitting the C for a B or an A in maths.... As for GCSEs, they use them to differentiate candidates, i.e. a student is more likely to be academic with 8A* than they are with A/B/C grades, although it isn't always the case, and although good GCSEs are favoured, it's not to say it's the be-all and end all, I know a guy with two offers for medicine with 6A*, and a guy who got none with 10. Medicine want people who can communicate, not academic bots.