Okay for 1, don't worry about that until youve actually got your results. You might have done alright, you never know and unless if youve failed (i mean as in not got a C) everything, i wouldnt recommend retaking all your GCSEs, it just wouldnt be practical. If youve passed everything then dont worry, unless youre going to oxford or cambridge your gcses arent that important, just try not to mess up your A levels. Really youve come to this realisation a bit too late but remember that GCSEs arent over yet, you can still try and do as well as possible in the exams you have left. As for taking a gap year, you have to stay in education by law so i dont think you could literally take a gap year and not be in education. Lots of colleges offer resit courses but thats mainly for maths and english but you may be able to find some for other courses.