As I understand it, if you have an untaxed, uninsured vehicle that needs an MOT, then pre-booking into an MOT station is acceptable. As you need the MOT to get TAX. But must be prebooked.
When driving a car, that is not yours, the owner, or registered keeper, MUST have FULLY comp insurance, and you also have 3rd party insurance, that gives you 3rd party insurance on their fully comp car.
To say you are the registered keeper of a car, and insured as the main driver, and your child is the nominated driver, when in fact they drive it, is illegal, and would void the insurance.
But the DVLA change and choose their rules to suit themselves, so anything goes..ie A bloke purporting to be from the DVLA approached me recently, says, I'll buy your SORN car, as we are gonna tow it (which they did with a previous car, illegally, and returned it, minus the front bumper!), so I complained to DVLA, they passed it on to their towing unit, who sent me a letter, which wasn't sealed, saying "not me guv!"..corruption or lies?