you can buy insurance for a uk registered car at checkpoint charlie, between trnc and RoC...
They always say its not a problem, but there is always a queue of brits at the duty office, every morning, on their 20th visit with new documents, trying to get a sign off for no duty and registration tax...
My main problem is that they dont understand kit cars... at all... I have a car that was brand new last year in april, and registered for the first time in November, but it was given an age related plate due to the donor vehicle...
The dont believe the copy of my type approval certificate is real, they want the registration document for the scrapped donor vehicle, and this is after i have had a cyprus MOT and SVA test.. its just a joke really...
Anyway, have all the required docs for yours, and you may be okay, but as a minimum you will need:-
6 months proof of residency in EU
6 Months proof of ownership of the vehicle such as insurance
6 months proof of working in EU (or 6 months EU bank statements)
EU type approval certificate or number for the vehicle
Good luck, you will need it