Best thing about it, especially if you look young (i've been accused of being 13!) and having a RHS job, is walking through the terminal and seeing the punters faces, you know all of them are thinking awww isn't that cute, he must be on work experience and must think he's a pilot, and then when they get on the plane and realise i am their pilot and see them turn a little white, and then grease it onto the runway, and for them to congratulate you as they walk off, tis a good feeling! going to football matches for kid's prices and then have a pint at the pub afterwards is also a good feeling!
If you have the confidence and enthusiasm to go into an interview and know sufficient information about the company, and for them not to think thank fook i don't have to sit next to this knob cheese for the next 8 hours, you'll do fine, regardless of age.