Whatever you do that isn't flying falls into the hobbies and interests category i'm afraid. Granted, it may enable you to give a few good examples of teamwork etc at interview, but as far as putting you significantly ahead of other candidates...no chance.
All that counts these days is flying time and it's many permutations and combinations. Generally speaking you want to be able to tickas many boxes that include multi-crew time, heavy/medium jet, turbo-prop etc...
Technician time will count for nowt.
Also if you are serious about airlines then the whole ethos revolves around seniority; basically get in as soon as you can as the number you get on day1 dictates your career for life with that carrier.
If iwere you i would't fanny around with the RAF, it's extremely competitive and they'll see right through you if you aren't 100% dedicated to THEM. Get that ATPL as soon as you can without putting yourself at seriois financial risk.