Try Harder
If you've had personal problems that have distracted you from your studies, the best thing is to resit the year, and get th equalifications that best demonstrate your abilities! You are quite obviously young, and as such impatient to get on with living out your dreams, but rest assured that you have plenty of time to acheive them - just give yourself the best chance.
Your posting here has already given you a good insight into the RAF: people will happily shoot you down the moment you open your mouth to say 'hello', and there's a hell of a lot of 'banter'. Deal with it like an adult; you can happily ignore people who chastise you for your spelling and grammer when, 3 times in one paragraph, the follow a question mark with a lower case letter. Start of a new sentance anyone? That said, poor spelling isn't necessarily a massive hurdle, I once had a Wing Commander write in the F707A that there was a "loose rivot on the l/h wing". Full marks for observation, but not spelt correctly. See where the important stuff lies? Better to have someone who's smart, and can communicate his or her point, than having a total pedant that spends the whole pay picking fault in others.
Rant switch to 'off', brew on.
Edited to add: Sorry to Northern Circuit for my lack of brevity!