I never had any trouble changing French/German discoverys to UK plates. Turned up with any paperwork,new mot/inspections
They checked the chassis number & uk plate info arrived few days later.
@dieseldog69 did you do anything special for yours to import with paperwork?
No, it was the usual MOT and chassis number check over, send monies and wait for papers to get the plates made up, my hassles came with HMRC and snail mail, them losing papers and then being told to do the waiting game whereby weeks pass by before anyone believes that there is a problem, it was a proper pain in the hole, I miss the good old tax office and the local DVLA offices where they were happy to rubber stamp you and get your problems resolved.
As far as I am aware the only problems ever to arise is if there was no CoC or previous case matriculation data to work from.