Hi there
Speaking from experience i can safely say that GNVQ's are acceptable in place of GCSE's but it depends on the airline. I attended the BA selction and apptitude day and they confimed over the phone that my Advanced GNVQ distinction was more than adequate in place of a lacking GCSE.
PS - One more point i would apply for an Avaition Medical ASAP to ensure that youre eyes are'nt a problem i bet there not but it safer to chek noe that further down the line when you have forked out countless amounts of cash !!!
Keep Flying.......