airborne_artist, in my personal experience, flight simulators are beneficial, due to the fact that they are the next best thing to actually flying.
I frequently practice lessons on there to reinforce the real lesson i had and to help me develop and correct any mistakes that i may have done before hand.
As for being a snitch, pfft!
As for the ACTUAL topic, at the end of the day a good personality goes a long way. Your in the age range to have your first interviews which ideally you should do ASAP, this will not only get you known but will build confidence and get a relationship with the careers officer.
From my interviews with the RAF they went very well, and i believe i could do reasonable well, one of the factors is that i was the youngest there and had experience in flying, on top of that i put a smile on and tried best and the outcome was good. I decided not to further myself with the RAF for many reasons.
So the best bet is at least go to an RAF presentation, they will tell you what is needed and everything you'll need to know at that current stage for joining the RAF (interviews, wars, aircraft etc)
Just make sure you have a back up plan (civil instead of military), in addition if you have not got a trial flight in yet, try get one booked (if you have the cash) as many people find that after their trial flight they decide not to go through with an aviation career anymore which can be due to a range of factors, scared (flying in a light aircraft is completely different to an airliner), possibly to hard, not what its cracked up to be etc.
PM me if you want any details about the RAF interviews or anything
Regards and best of luck, Nathan