You definitely need to get confirmation on these age limits mate, although I am certain you are well inside.
Serving Airmen are NOT capped to age 27 - I was a serving soldier who transferred at age 31 alongside blokes from inside the RAF of similar ages and circumstance.
As has been previously advised, get the info from PSF and don't worry about any trade backlash. For starters, the RAF is keen for NCA in all branches never mind for Pilots/WSOs. You're bound to get a bit of stick from the knockers ('doubters' not NCOs
) who wish they'd done it themselves but if you're genned up and well prepared you'll be at an advantage to the DE candidates who are attempting selection, simply through your previous experience.
Best of luck.