GCSE is the grades you get in the UK.
I think it stands for general cetrificate in standard education? If not then looks bloody good to me,lol
I got a few of them, but my grades are called 'O ' grades, before the GSCE's came in
so a song ?
depends on how good you are at playing but if you are good at finger picking then might I sugest " tears in heaven" by Eric Clapton. I have heard one guy ( apart from Mr Clapton ) doing this and it sounds amazing. No slide in it thought, but ye might be able to put a slide in? not too sure, but certainly for finger picking, this song is superb.
Ken
p.s. Good luck, but you got months before you do it, so start practicing
ye get some that are cut out for the job and others just get by from pretending