Never heard of insurance for GPUs but I doubt there are any insurance providers offering insurance for GPUs that are used for mining but I might be wrong.
Not in UK and not anywhere else in the world there is warranty or insurance for graphic cards used for mining. In my country the biggest PC parts supplier is selling them with 6 month warranty and it includes mining strangely. As long as they are doing so I believe they have had not any problems with cards being burned in the first six months from mining, especially 2 fan cards.
If you buy new the card and you are sure that is new in factory sealed form , then nothing to worry about about warranty or insurance, the card will behave perfectly both gaming and mining unless it comes damage from the factory sealed box which of course you can return it back.