I see Dave has had issues with Reis Paul but I will share my experience.
My car is insured with them on an agreed value. I needed to show them my competition license as well as a few photos of the car competing.
There was no need for motorsport papers as the car isn't log booked as its not needed for hill climbing.
A non race national b license is under £40 and requires no tests etc.
As you have used your car competitively and have photos maybe enquirer with REIS?
May be worth spending 40 to save a lot more?