These policies are not something you 'download from the internet'. They are insurance policies issued by a company that indemnify the buyer in the event that some fault with the land title or the building regulations associated with an extension he perhaps constructed without BR approval shows up later, after he has sold.
In the case of something going back to 1898, it must be because there is some minor defect in the title - perhaps related to access to the property (a guess).
He needs to phone an insurance company to ask about what policies they can provide and how much (typically a couple of hundred - depending what is being insured). Norwich Union (Aviva) used to be big in this area of insurance.