I don't know anyone else's view on this, but I would feel much more confident turning up to the interview feeling like I'm ready for everything as opposed to only being ready for the interview.
The issue I have is that I'm now 22 and my time to get in as a pilot is running out. I know how important it is to exceed during all parts of the application process and would like to know what you guys would suggest me doing?
Fitness is important but so is evidence of your belief in a career in the RAF.
You are 22, "what have you done to foster your interest in a career in the RAF?"
If you are a university graduate that can explain your late application, if not what have you been doing?
You are only a few miles from two major front line stations, have you organised visits there?
As you imply you are unfit, what was the reason that only now are you embarking on a fitness regime?
These are questions you need to prepare for.