This article will explain how you can change a .UK domain’s legal registrant/owner.
Registrant name changes for a .uk domain name (.co.uk, .me.uk, .org.uk, .uk) can only be changed via the .UK Governing Registry, Nominet. This change is the equivalent of changing the ownership of the domain name.
This can be done using the online Nominet account portal. This can be accessed via the following link, using the necessary Nominet login details (which you should of received when registering the domain name):
Nominet charges a £10+VAT fee for ownership changes.
More information on this can be found here: https://www.nominet.uk/transferring-your-domain-name/