Hello
@wizbang and welcome to this friendly and supportive forum. There is a wealth of shared experience of dementia to be found here, so I am glad you have found us.
I am sorry to read of your husband's recent Alzheimer's diagnosis. It's tough for sure, even if you were half expecting it.
The following link may help with your question:
Drivers with dementia must tell their licensing agency and car insurer straightaway. Find out more about UK law on driving and dementia, and what happens if these rules are not followed.
www.alzheimers.org.uk
I hope you will find this forum useful for sound advice, good suggestions and understanding from members that really do want to help.