According to the CAB, there is no general death grant:
Some people do not leave enough money to pay for even a simple funeral. If this happens, the person arranging the funeral will have to pay for it, although other relatives or friends may be willing to contribute. There is no general death grant, but if you are in this situation and you receive a means-tested social security benefit (such as income support) you may be able to get a payment from the social fund (known as a funeral payment) to cover the cost of a simple funeral. Even where a funeral payment is made, it may not cover the full cost of the funeral and you may still have to pay the difference.
See
here for more info.