My advice would be to do all of the above and ENGLISH. Many people fail to get an interview with an airline simply because of inability to complete the on-line questionnaire with accurate spelling and punctuation!
Also I suggest doing aptitude testing (costs £175) through the GAPAN scheme at Cranwell before embarking on expensive flying training. AND make sure that you can get a Class 1 medical. Good idea to do both of the latter before making choices as if it turns out you have no aptitude or cannot get the medical then your A level choices are irrelevant.