Registrant name changes for a .uk domain name (.co.uk/.me.uk/org.uk/.uk) can only be performed via the .UK registry, Nominet.
This can be done using the online Nominet account for the domain. This can be accessed via the following link, provided you have the necessary Nominet login details (which should have been sent to you when registering the domain name):
https://secure.nominet.org.uk/auth/login.html
Nominet currently charge a fee of £10+VAT for ownership changes.
