If I remember correctly, it doesn't cover everything you would probably like to be covered. However, you needn't actually worry about it until you're actually moving in on the day. There was a Endsleigh insurance rep. in the halls office [where you will collect your key etc.] that explained everything to me + I sorted out the insurance there and then, which was really quick. It's not that expensive too - something like £8 a month
[EDIT] I think you can check out the Endsleigh website and give them some details + they'll tell you what is covered in your halls etc.
Before you purchase extra insurance check you parents home contents insurance many home insurers give extra cover as an optional extra or as part of the policy for students belongings.
any one claim. 4. Contents at University/College We will pay up to 15% of the sum insured for contents, for loss or damage due to any cause insured under paragraph A of this section 2 to contents temporarily removed from the home while a member of your family is attending college, university or boarding school. copy from insurance plus at direct line but lots of other insurers gave this cover too.