If you can pass the selection procedure, which for NCO aircrew you are overly qualifed for (English, Maths, Science - anything else just gives the selection board something to talk about) then just go do it, RAF will give you better pay, higher rank, from the get go.
I would expect any compos mentis selection board to ask you why you have 13 quals at O level, at the age of 18, rather than say 5-8 at O level and 3-5 at A level, so you might like to get the answer to that one ready.... that's not meant as a criticism, but if I were on the board that'd be a q I asked, so best be ready to answer it.