DMB or Drivers Medical Branch at Swansea deal with this stuff, so address to them, it will get sorted sooner.
As I had a declared disability I had to take a disabled test, in a car with no modifications at all, not needed for my disability, but test lasted from 14:00 to 17:15.
I was told all this crap about limited license etc, as it turned out it was all crap, as far as my case went.
Hope you get on well, and good point above about insurers not being able to load for disability.
tabetha