Take a look at the following site:

http://cableorganizer.com/dymo-repla...bels/index.htm

You may be able to use your existing label maker with a simple change of tape. I would image that a UK supplier would carry this type of tape. After all labeling cables is a big business.

If that does not work out, look for a supplier of heat shrink labels. These labels slide over the cable and then are affixed with a heat gun (i.e. hair dryer).