Motor insurance
Most motor insurers do not charge an extra premium for volunteer driving. There is a code of practice written by the Association of British Insurers which can be downloaded below. It will allow you to check the position of your current insurer.
Some insurers require you to inform them before you commence volunteer driving, even though they do not charge you an additional premium.
The position of individual insurers may change with time, so it would be good to check directly with your insurer anyway.
Note that, if your insurer says that they want to charge an additional premium, you could challenge this. Sometimes the person from the insurance company does not know the company's position on this issue, or will take the matter up with the underwriters. Here is an example of the experience of one driver from the Hampshire Good Neighbours network:
'I ... wanted to let you know about my issue with **** Insurance where we were told that we would have to pay an extra premium to carry out our Good Neighbour tasks. I used the information and guidance you gave me and fortunately spoke with a very helpful advisor on their helpline, who first of all said that yes we would have to pay but she thought this was unfair and then went out of her way and contacted the underwriters which culminated in us not having to pay.’