If you develop a health condition or disability you should inform your car insurance company.
It can’t charge you a higher premium or increase your excess without evidence that you’re an increased risk.
If you drive a vehicle that’s been specially adapted to meet your needs, the insurance company can increase their charges to offset the increased cost of repairs that might be needed in the future.
Some insurance companies and brokers specialise in insurance for disabled drivers.
The British Insurance Brokers’ Association (BIBA) has a database of brokers that you can search to find those that insure modified vehicles.