Double adapter as everyone will be trying to plug their iron into a single plug socket. Two sets of wash kit, one for your locker and a "real" useable one. Pictures of your bird in a state of undress to be strategically placed on the inside of your locker so that the Corporals have something to look at other than your kit! And porn mags, the unofficial currency of ATR's everywhere!
A little basic first aid kit wouldn't go amiss; it should have zinc tape, plasters, ibuprofen cotton wool and a bottle of surgical spirit for your feet and any minor cuts needing cleaning....oh and a rope to bite when you use the surgical spirit.