Do they have somewhere parcels can be delivered to? We took less and less for each subsequent DC and then sent things they actually required.
Most new halls provide electrical items in the kitchen and dont allow extras.
Check the size of the bed - some are small doubles or extra long.
Dont take too much kitchen stuff - they may only have one small cupboard.
A sealable box for any food or drink treats to keep in bedroom is handy - speciality tea bags easily 'walk' as do chocolate biscuits....
Do they have an ensuite? If not then plastic flip flops for the shower etc. And a small basket/ bucket for toiletries. Loo roll ( might end up taking your own back and forth)
If ensuite, check if shower rail and curtain supplied.
Coat hangers.
Door mat for wet/muddy shoes to dry on.
Check what kind of power extension sockets are permitted.
Cushions to make it more comfy sitting on the bed.
Room freshner

Something to attach various key cards etc to one's person - various options available.
Suitable footwear and clothing if travelling very far north

sounds daft but one DC had girls turn up with slip on 'pumps' and flimsy jackets. Not good when the first snows hit. Hopefully yours has more common sense!
Be thinking of you. By the last one I wasn't allowed to go. Not good at hiding emotions..