You need to pay £105 to DVLA to take the number off your current car. That includes the £25 for a years retention certificate. That means that you can assign the number plate onto another car with no additional charge within 12 months.
When the dealer goes to register your new car, he can do it using your retention certificate, meaning the new car will have your number on it from day 1. There will be no money to come back from him as the vehicles first registration fee (part of the OTR charges) have nothing to do with the allocation of a personal number plate.
I would ask Direct Line if they would amend your current policy to take into account your plate change for free. After all, all they have to do is type in the new reg number (when you get it from DVLA) an email the amended certificate of insurance to you.
Whilst your thinking about swapping your number plates, it may also be a good time to think about putting the original lights back on.
