Hi,
A Dutch car has it's own licence plate. From the day the car leaves the dealership until the day it gets 'junked' or crushed it
remains the same plate number. The insurance and tax are not linked to the licenceplate, so if you buy a car, you will also need
a insurance and pay for tax. I presume the car will be exported to the UK, so no need to worry about the tax.
For what year are you looking ?? If the car is younger then 8 years and 2 months, you can get a refund of the sales tax.
It all depends on the exact model and year.
German cars are different . . . the carry, like the UK, a personal plate. So if you buy the car you will need dealer plates
to get to the customs. There the plates will be changed for export plates. In some cases the dealer ship will help you with
all the necessary export papers in which case it will safe you a bunch of work.
If you need more explanation just let me know . . .