I wouldn't worry too much about them, they are built up far too much by the schools, have to remember they want you to do well so the school looks good. I'm just finishing my first year at university and not once have my GCSE's come in handy, you need them to get into college and thats about it. 5 C grades is all you need, can do anything with that, just aim to have a couple of core subjects included in that 5. ***Disclaimer*** I hold no responsibility if you just get 5 C grades and find you can't do what you want to do, this is only from my experience.