Congratulations on having fantastic results - I also like that you set your sights high!
But please remember that A Levels are significantly more difficult than GCSE; if you work hard and succeed at A level then think about courses and THEN university.
Sorry to put a downer on it but I know many people who stumbled blindly into A level and bit off more than they could chew.
Dude, the government are happy if you get 5cs . . . stuff like medicine at oxbridge ask for about 9A*s, 11 of them plus one C in a subject that not many unis care about at gcse won't do you any harm. . . you're fine. I got a C in ICT but I did do it in year 9, did you?
Unlikely. Although, if you're at a job interview and say 'I have 11.5 A*s and a C' then you might get asked what the C was in. But once you tell them it was IT then they probably won't worry so much.
Its completely obvious to the outside observer you weren't the one at fault and that the school cocked up or the board moderated the coursework down or something. I wouldn't worry about it.
This guy must be in year 12 sixth form. I highly doubt anyone with results like that would even be worrying about a C, or come to TSR to ask about it, especially after 6 months.