Tuppence worth just adding to the above posters
2 x Padlocks (sturdy ones)
Coat hangers plenty of not your mums pink ones
Electrical tape ---black
Elasctic Black/Wide
on washing and shaving kit get down to pound strechers and buy a heap (spares,locker inspection etc)

plenty of razors (decent ones not bic orange) dont be a ming and share reuse from bin etc
dont bring any "gucci kit" 1) you wont be allowed to wear it 2) alot of gypos about 3) get used to the issue kit
Black marker pen again above ref no 2 your oppos are to be trusted in a firefight but not in barracks when they have lost something mark you kit up as soon as you get it!!
Bank account ?! get one before you go or there be a delay in getting money
Passport photos take some with you a)Sect commanders will need them for your file (dont know if this has changed) b)For a passport
Leave all your fancy PSP's and DVD's etc (Some mong/chav will take this anyway and watch his face later on where 2) happens) personal stero/mobile phone
Leave at home attitude\cadet stripes\sas books etc
Was an instructor in 97-99 so more than probs things have changed, but enjoy its the first rung of the ladder, steep learning curve blah blah blah...