I do know that a faulty speedometer isn't admissible as a reason for speeding, for example. It sounds like it should be, but then again, were that the case
everybody in the world would use that excuse. I'd imagine that a 'faulty' cruise setup would be regarded as similarly so. That's assuming that you could prove your cruise was faulty - which I strongly suspect it
isn't. But even if you
could, there'd be no point, that would come under the banner of 'you're not maintaining your vehicle properly'
I seem to recall you're entitled to see the photo/proof of the 'crime', however, this can take blah blah days/months to occur, and if you win, get the points revoked. Hurray! On the other hand, if you appeal and you lose, you've then
lost the ability to take the 'cheaper' 'better' option of the naughtycourse, and get stuck with the far more devastating points and a fine. Clever, isn't it? I think these same people invented the 'if you're not a witch - you drown' cucking stool.
Hoping you get offered the naughtycourse, and no points etc.
http://www.which.co.uk/cars/driving/driving-advice/dealing-with-speeding-tickets/how-to-contest-a-speeding-ticket/