Not a specific recommendation for accommodation, but Beaumaris would be a great base. I've visited all my life and love it. I took my young children just a few weeks ago and they had a great time too. It's on Anglesey but not far from Bangor. It has a pier for crabbing, paddling pool, playground, excellent fish and chips, ice cream parlour - and a castle at the end of the high street.
Perhaps try the Menai Cottages website for a place to stay. They're really helpful if you give them a ring. Pilot Cottage in Beaumaris is right on the front with views over the Straits to Snowdonia so might be worth a look.
There's plenty to do in the area too, but you may be busy at uni! Hope it all goes well.