Boots chemist and others stock a mouth spray for dry mouth syndrome Which helps me a lot it's basically a lemon flavour water .also Tring to breathe through nose might help .obviously check incase you have an allergy to any ingredients but it is very basic
Best contact dvla it depends entirely on you particular case generally type 1 would be a problem. I was diagnosed after I retired with t2but I can still drive cars your nurse might be a help as mine gave me several leaflets about the laws from dvla.