I also agree. Retain an attorney to appeal the assessment if you believe that the assessed value is higher than the property value as conducted in your town. According to your statements, it sounds like your assessed value is higher than comparable homes in your community, so that is a circumstance favorable to your position.
I agree with Nicholas that the first step is to contact your insurance carrier and advise them of the suit. At that point, the company can step in and potentially take actions on your behalf. If the insurer does not accept the claim however, it is then potentially advisable that you should seek legal advice.
As the previous attorney commented, UK law would govern a cause of action that occurred involving a British university. Note that in the UK, the legal system differs in a number of ways but one critical difference is that unlike the US where each side bears the costs of their legal representation, in the UK, the loser pays for his adversaries counsel. Therefore, if you intend to sue, be very clear that you understand the ramification of your decision in advance of making it.
You did not did not make clear why your insurance carrier first said there was valid insurance for you and then reverse that determination later. Given this confusion, it appears that you should probably consult an attorney regarding your rights to insurance coverage before embarking on another path to address problem.
The language of the insurance policy controls the coverage regardless of what the letter unilaterally states. However, if the letter simply reiterates what is already contained in the policy then it appears that there is no coverage for the accident.
From your description of the situation, it does not appear that the seller has shirked his legal responsibility to make the roof repairs but the efforts have not succeeded in correcting the problem. Before embarking on a litigation path, it might be prudent to work with the seller and/or his agents in repairing or potentially replacing the roof which sounds like your preferred course of action at the moment. Litigation is a costly and time consuming venture, and once you begin a lawsuit,...