how do i help my deaf non verbal grandson who is constantly banging his head.

This might be something that improves as he matures (I'm not sure) but I do know it's likely triggered by stress factors and emotional dis-regulation. Until the trigger can be mitgated in the mean time it's important to protect that developing brain. This link is to an example of a helmet on a US site, and I will look for a UK version too, but hopefully this might prove useful in the interim: https://guardianhelmets.com/cranial-helmets-for-head-banging/

Edit: (P.s.)
Here is a UK seller of the helmets if you and the family think one is needed: https://www.healthandcare.co.uk/face-and-head-protection/head-protex-soft-shell-helmet.html

This might be something that improves as he matures (I'm not sure) but I do know it's likely triggered by stress factors and emotional dis-regulation. Until the trigger can be mitgated in the mean time it's important to protect that developing brain. This link is to an example of a helmet on a US site, and I will look for a UK version too, but hopefully this might prove useful in the interim: https://guardianhelmets.com/cranial-helmets-for-head-banging/

Edit: (P.s.)
Here is a UK seller of the helmets if you and the family think one is needed: https://www.healthandcare.co.uk/face-and-head-protection/head-protex-soft-shell-helmet.html