There is Marmalade insurance, I’ve considered it but haven’t got with them yet, their learner insurance does build no claims, basically the car is insured by say a parent on their own insurance company / policy , the learner is then insured separately by Marmalade for a pre agreed mileage number, the benefits are that if there is a accident it doesn’t affect the parents ncb, when the learner passes their test, the policy converts at the same price for the year, the downside is Marmalade is run on a black box app arrangement and from reading reviews it’s pretty draconian and they fine the driver for what they deem risky driving, not just for example speeding, but ( subjective ) excessive breaking or cornering speed and acceleration, this has put me off going through them, the policy’s do seem cheap though but I bet they get their money through the punitive fines.