Did they take the objects back? - in that case it would be attempted theft. ( altho you intended to permanently deprive, you didnt)
The security guard cant ban you ( too junior) so it has to go thro the shops procedure - and I thought they wrote saying - you cant do near XYZ... but I dont know as I dont know anyone who has done this ( unlike beating someone to death with a spade etc)
Surprisingly I am more concerned about taking ident and copying it. But what is done is done
The next steps are wait and see ( it almost always is on this thread and that is because you cant control anything or vary it - any intervention is likely 'to make it worse')
You should also keep quieter - as far as I can see your univ can chuck you out if these facts are admitted ( dishonesty)
oh, in your spare time, write two sides of A4 reflecting on what you have done, how stupid it was, and how you never never...etc - it may well come in useful later on