Being a relatively low level traffic matter the officer would simply report you for summons on the spot for DOWL and/or no insurance and CPS would not be consulted. Given the question over potential insurance issues the officer would then likely sieze the bike for inspection slow time so that all evidence could be presented to court.I believe the police may lack a statutory power to issue a penalty in respect of whatever offence this is so it would go to the CPS (wouldn't it?)
I will add that the above scenario happening via a stop check would be so unlikely as to be not be worth a consideration. The real issue (as others have said) would be if serious injury or damage occurs. Even then, a police proscecution may be unlikely but that would not prevent a civil claim being lodged which could effectively ruin the rider. In short, the police are the far lesser concern here IMO.