If you booked your car in for a MOT at a garage say 5 miles further on from where you wanted to take your car you would be able to drive it to the garage for the purpose of the MOT.
If however your car broke down before getting to the garage and it just happened to be at the place where you wanted to take you car to the one would suppose that it would be perfectly legal to leave the car at this new place while effecting repairs.
It's not a good idea to ask on this forum if something is legal and totally ignore the advice given or dream up any scams to move the car in a legal way that can be misconstrued as being put into effect just to bend the law - in other words don't now try the above
just to move your car