It's a very varied job. Your day-to-day routine depends entirely on what sort of aircraft you work on.
Rotary (Puma, Chinook, Merlin) - Training flights, work for Army exercises, deployments abroad etc etc etc
SAR (Search and Rescue) - sitting around waiting for a telephone call that'll see you rushing out to pick up some prat that's fallen off a ledge in the mountains, some kiddie swept out to sea on a lilo or some fisherman that crippled himself out at sea. etc etc etc Some hair-raising flying, followed by issue of medals and obligatory interviews with the press.
Hercules - Supervising the Mov Ops guys loading the aircraft and making sure everything runs tickety-boo during the flight OR sitting in the back with 70 grumpy Paras...getting your own back on them by keeping their sarnies warm.
Tristar / VC10 - Supervising the loading of passengers and freight (if transport sorties). Trips around the world, nice hotels, lots of beer. Get to sort out the customs paperwork, where required. OR air-to-air refuelling work.
If you want a real idea of what it's like, contact your local AFCO and they will organise for you to attend an overnight visit to RAF Cranwell with the Non-commissioned Aircrew liaison team. (these visits are excellent).