Really urgent question on English education, please help.?

I'm 15 but I'm home-schooled. The chances of me moving back down to London are very high and I don't think I'm getting anywhere here education wise so I think I'll take my gcse's down south. I'll be moving next year after April time. I'm in year 10 now and I finish year 10 this July, start my final year in September and finish around April/may time. In which I'll be moving. So, can I repeat as of September 2012 my final year of school? Or can I just do my A-levels and skip Gcse's. If I haven't made myself clear, please tell me. Thankyou.