Accommodation costs are one of your main expenses of university. It is worth spending the extra time to help make sure you'll have a hassle free year. Make sure the house is in a convenient location for pubs, shops and transport links to the campus. Walk the route back from the bus stop at night and make sure you feel comfortable. When you're at the actual property make a thorough check of the condition it is in:

Exterior - does the roof look sound and water tight? (look for signs of damp on the ceiling when you go inside), are the gutters and drains clear?, is there any woodwork rotting and unsafe?, is the garden tidy and trouble free? (you'll be responsible for its upkeep), are the external doors and locks secure?, are the windows clean? (you'll be responsible for keeping them clean)
Interior - has the house got enough furniture (in a decent condition) for the occupants?, is there sufficient space in the kitchen to store and prepare food?, is the fridge/freezer big enough?, do the electrical appliances all work?, is the heating system adequate?, do the taps/toilet/shower all work and not leak?
Safety - is there a copy of the CORGI gas safety certifcate? (a legal requirement), has the electrical wiring been checked in the last 3 years?, does the property have working smoke and carbon monoxide alarms?