I got this email today. I'm pretty sure it's ok but it links to a non-secure site and asks me to upload a copy of an identifying document, so I wanted to make sure.
Recently you registered or modified the contact information for one or more of your .UK domain name(s). As of September 22, 2014, Nominet (the operator of the .UK domain registry) requires all accredited registrars to validate their contact information. You can read about Nominet's policy at: http://www.nominet.org.uk/become-registrar/registrar-agreement/data-quality-policy
The following domain name requires verification by 2014-11-05:
In order to ensure your domain name(s) remain active, you must now click the following link and follow the instructions provided. You will be required to upload a document to prove that the name and address assigned to your domain name are correct.
Failure to follow the above link and complete this process will eventually lead to the suspension of your domain name(s).
If you have any questions, please contact firstname.lastname@example.org.