I was sorry to read that this was worrying you littleannie. My mum and dad are in an almost identical position, Dad is 85, mum doesn’t drive and they are a long way from the nearest large hospital. Of course I don’t know what the plans are but this is what I think will happen.
The 50 hub hospitals are just the ones that will be used for the very first set of vaccinations with the supplies they are getting this week. Dad is not expecting to be in the very first group of 400,000 people to be vaccinated, he is thinking that care home staff, hospital workers and older people already in hospital will get the first doses. More hospitals and eventually places like GPs surgeries will be added to the list of locations as the NHS takes delivery of more doses.
I am expecting that they will get a letter inviting him for his appointment, and that there will be a way of contacting the NHS to explain if there are any problems with getting to the site. There are bound to be many people in a similar situation. Then the NHS can arrange an alternative site, or even get someone to come to the house, even though, like your husband, he is not housebound.
They definitely want as many people as possible to get the vaccine so I’m expecting that they will find ways of getting it to everyone. Hope this helps.