Paros24,
Let me ask you a question. Is your house insured? If yes, then yes, it can be insured. I live in a 130yr old house and review insurance every year. I have never been asked about this. Sounds to me like their surveyor is trying to get you to do work that would be the responsibility of the buyer (if they so desired to do this). There is no obligation to do this. Of course, it is good practice to do it, but to say the sale cannot proceed until until it is rectified is just plain wrong. They may choose not to proceed because of it, but that is a choice. Similarly, they may choose not to proceed if, say, for example, the roof was in poor condition.