I have never done this, but this is what i read from the RDW website. (RDW = dutch DVLA)
Link below is the procedure in dutch. Use google translate.
https://www.rdw.nl/Particulier/Paginas/Uitvoeren.aspxExport from the Netherlands:
You or seller has to go to RDW agency (=dutch DLVA) Not to a postoffice!
No need to make appointment. Just show up. No need to bring the actual car.
Paperwork you or seller need to bring:
Licence register paper part 1B. (This links the name of the owner to the car. The seller have this)
Licence register "overschrijvingsbewijs" or "Kopie deel 3" (this is to transfer the ownership. The seller have this)
ID
Licence plates from the car need to handed over.
Paperwork you receive from RDW:
"vrijwaringsbewijs" this is for the seller to prove that the licence number is no longer linkt to him.
New licence register paper part 1B. (with the new owner's name on it)
New licence register paper part 2 (prove of export?)
Costs: €10.77
In UK you need:
Licence register paper part 1A (car data. You will get this from the seller.)
New licence register paper part 1B, and part 2 (you got these from RDW)
If you want to drive legaly on Dutch roads after the export procudure:
The car needs temporarely licence plates. Same number as the original, made from cardboard. White background, black letters.
Car need to have valid APK (MOT)
Car need to be insured.
In UK you need:
Licence register paper part 1A (car data. You will get this from the seller.)
New licence register paper part 1B, and part 2 (you got this from RDW)
RDW agency's:
https://www.rdw.nl/overrdw/Keuringsstations/Paginas/adresoverzicht.aspx?Path=Portal/Particulier/Auto/Uitvoerenopen weekdays 8am to 5pm