Motability says:
“Your vehicle needs to be used by the disabled customer or for their benefit.
This does not mean they need to be in the vehicle for every journey.
It means other named drivers in the same home can use the vehicle for:
Shopping
Visiting family
Other routine activities
As long as the disabled customer benefits.”
I would say your husband will benefit from your attendance at the wedding – you will be representing him, and taking your experience of the event home to him. I cant see anyone arguing with that.