It may be difficult to buy number plates for a new car, because of the complexity and sometimes bureaucracy that one has to undergo. In the UK however the situation has been eased up due to the development of online access to number plates.
The Driver and Vehicle Licensing Authority is the body charged with issuing vehicle registration numbers and they have decentralized their services so as to be more accessible to the public. You can purchase a registration plate from one of their dealers listed on their website at https://www.gov.uk/number-plate-supplier. These dealers are listed according to postal locations and from there you can search for your nearest dealer using your postcode.
The second and most efficient method of buying a registration plate is doing it online. In the UK there are various sites that deal in number plates and you can place your order directly with them and simply wait for home delivery of the number showplates. To buy at these sites you simply need to access their URL and you will find a portal that is in most cases user friendly which you can use to make your order. To make payments you only need either your debit or your credit card.
There is also a third option which is buying registration plates at auctions. As a car owner, you can choose to buy or sell a registration plate through specific forums. It allows you to set prices and is also safe and secure.
On some occasions you are required to present certain legal documents in order for a successful sale or transfer of a registration plate to be completed. These include something to verify your identity and proof that you have legal ownership of the car. However, if you want to buy number plates that are just showplates then this will not be necessary.