It used to be that you could pay to compound a kennel name for life, but now any new ones have to be paid for annually. The cost depends on how you pay, if you do it by direct debit then it is cheaper.
Currently it is �70 to register a kennel name which includes one years' maintenance, then �20 per year or �17 if paid by direct debit.
It takes a few months to set it up, as you have to submit six names, then you have to wait until your choice is published in the Kennel Gazette to give anyone a chance to object if it is too much like theirs, then you are notified if it it ok.
I had a friend who let her affix lapse, and luckily after several years she was able to get it back again by paying the fee, but if someone else had used the name she would not have been able to do anything about it.
You can download an application form from the Kennel Club site:
http://www.thekennelclub.org.uk/item/371