Toilet roll.
I agree with the not going to Ikea for crockery, it will be stolen, used by others and not washed.
I'd suggest a washing up bowl, if the sink id full of others dirty cups he can still wash up.
Clothes, add some winter stuff, it will be Xmas before he comes home.
Unless he has his own en suite then flip flops for the shower. Towels obviously too. Dressing gown / robe if he is using shared facilities.
He will need notebooks / paper / folders etc, USB sticks are useful for backing work up.
A list of phone numbers and dates of birth of the family so he can phone gran on her birthday or SMS his sister (adjust for relatives he has) depending on your child a box of Xmas cards to send.
Drawing pins, there is usually a notice board.
A list of things to do soon after arrival eg register with a GP and a dentist. Get the right form for free prescriptions. Insure his contents, TV licence if he has a TV, bus pass if he needs one.
A mini first aid kit with some pain killers, plasters etc.
Does he know how to make a bed and operate a laundry washer?
Spare tooth brush and tooth paste, flannel etc.
Salt and pepper and favorite ketchup.