DVLA
Below are documents and information sheets regarding the DVLA

DVLA Documments
Application to register as a Number Plate
Supplier
V940
VTL301
Application for a trade licence form
Application to register as a number plate supplier. Supplementary form
V940/1
Information
INF46
Registration numbers and you (dvla documentation registration plates)
INF57
A brief history of Registration
How to import your Vehicle into Great Britain (GB)
INF106
2021 Vehicle registration numbers & number plates