Hi Naomi. Legally, there is probably nothing to protect him. It will simply be a matter of negotiation.
I imagine that his contract will state that he has to keep the and insured as long as it is in his possession. As to how long the finance company has to collect the vehicle once the agreement is concluded, it is likely to be whatever is deemed reasonable.
He can either argue with the finance company to sort out an alternative, such as dropping the car off to a local Skoda dealer, or simply keep the car insured for another couple of days – he should speak to his insurance company about how much this would cost (probably very little). It won’t cost him anything to keep the car taxed, as he has already paid for January’s road tax and won’t get anything refunded from the DVLA.