After your age in years and months ice breaker followed by why do you . . .
how would you answer this - what have you done to further your interest in the RAF?
Acceptable answer is: I joined the ATC/CCF and reached the rank of Sgt (or higher).
Alternativly, there were no ATC Sqns or CCF within 15 miles.
Unacceptable there were no . . . within 5 miles.
Get a map and mark where all the RAF Out of Area (OOA) are. Learn them.
Learn the RAF aircraft types. Don't forget the egg beaters.
What do you know about Typhoon and JSF? (Don't know about JSF or tranche 3 of Typhoon? get researching).
BTW You do NOT want to be a navigator. They changed the name and career prospects. Does EFA or JSF have a back-seater?