How would it work if you claimed tax back but you did not have business insurance for your car, so therefore not authorised to use your car.
I doubt HMRC would care and as far as the RAF in concerned you would have to check QRs to see what if any regs you had busted. Hardly something they are going to find out...and easily rectified because getting "business use" on you car insurance is normally free of charge and just a phone call. I say normally because just a few years back all car insurance companies provided this for free...just recently when I did it for a new motor, my existing company wanted paying for it. I told them to bugger off and went elsewhere.