Just curious but I wonder what would happen if/when you went back to Kwik Fit when the all-season tyres were in need of replacement if you didn’t have the original tyres on the car. I suppose it’d depend on if they even noticed but it’s something to think about. Going all-weather permanently could result in you having to pay for all tyres for the length of the lease as the “original” motability approved tyres would never get to the point of needing replacement because of lack of use.
One practical option (assuming you have the storage space and can physically manage or arrange it) would be to buy a spare set of wheels and go with the standard tyres during the “better” weather months, and only use the all-season tyres during the months they’ll really benefit you. Hopefully you’d only end up changing the wheels twice a year but it is one possible solution
"Man is born in freedom, but he soon becomes a slave, in cages of convention, from the cradle, to the grave."