For what it's worth, I recently sent off my application to Cranwell, and while the medical requirements are different for the RAF, my history of hayfever [last suffered aged 15 in 2000] and childhood asthma [unsure of details, but in medical notes as 'precautionary'?] did not exempt me from any aircrew branches in the eyes of the President of the Medical Board.
My coke bottle-bottomed glasses, however....
[I wasn't going for aircrew, but still had to declare all 'deficiencies' to the board prior to an OASC date.]