Buy a .CO.UK Domain
If you are going to book a domain with the extension .CO.UK, you can see that it is a fourth most popular top-level domain extension worldwide. The domain extension .CO.UK comes after the .COM, .DE and .NET. You can not register the domain name directly under the .UK, rather you can use the second-level .CO.UK domain name for registration.
The domain name with extension .CO.UK is most commonly used for the second-level domain of .UK extension, which is now followed by the .ORG.UK domain extension. You can register the .CO.UK domain name directly with the nominet which has the governing authority of the .UK domain extension. OR Also you can register the domain name via the member of a nominet.
After registering the domain name with the .CO.UK or .ORG.UK, you will get that the registration fees covers the time period of two years without considering that where you have registered the domain. And also the renewal fee for each covers the period of 2-years.