I am with Glos Guy on this one it is you who would be held responsible, if you were involved in an accident and someone was injured your insurance would be invalid, you would also receive points on your driving licence. You could end up being liable for the claim, bye bye motorhome.
You state you without your Motability vehicle for 13 months, did Motability supply a hired vehicle and how did the vehicle manage to pass all its services checks.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.