You're actually going to be responsible for the people who fix the aircraft, not doing the job itself. May sound like semantics a this point, but save all of these replies, read them in 5 years time and say "Ooooh yesssss....., now I understand". Very well done on qualifying. My advice (it's free of course), be fiercely loyal to your subordinates, even if you don't fully understand why, but always try to see the big picture ie. never forget you all work for the big cheese somewhere. Your age and maturity are plus scores for seeing the arguments from the other side of the table. Your WO/SNCO's will run it for you, but as an Officer you are always responsible, no matter who it is who screws up, so always know what's going on in your area of responsibility.
Above all else - have fun. There are some fantastic facilities and perks available, so go off and enjoy them, you will get plenty of opportunity to donate your pound of flesh for Her Majesty, so just regard it as an advance on your account.