Ralf - That must be an exception, since i am pretty sure (since been recently having a little queste on the subject recently) that delta is not really concerned about CE categories due to the type of customers the intend to service, as Polwart advised above.
I have been considering to do a ce inspection on my boat (also a delta) but noted that the eu rules on it in the netherlands can practically only be enforced the moment i would sell the boat to another private person, which would then be against the law.
How i understand it (cutting a few corners now), CE was intended to ensure a certain quality for batches of boats being built in for example low labor cost countries, but implementation of EU laws apparently dont make any exceptions for ex commercial crafts: There are no real lupeholes other than racing boats, rowing boats and experimental craft.
There furthermore seems to be a lot of- in my opinion- rather suggestive information on 'how bad it is' to have a non ce approved boat, but personally i have been mostly reading it on websites of surveyor companies who offer you post inspection surveys for considerable amounts of money. The dealbreaker for me was that although i could get it certified for a 3 digits number, my yanmar 4LH old school turbodiesel (prior 2006 engine) needed to be tested on emissions and noise and i think that it is as eco friendly on emissions as an east german trabant car would be, so i dropped the whole thing and promised myself not to sell the boat.
Above is experience on this subject in the netherlands and i am not sure how it is exactly dealt with in uk legislation...you will also most probably need to provide a manual (after all some warnings are not more than logic : dont put your boat in the bathtub or deflate it in the middle of the ocean!) but there are plenty better examples of such a manual to be found online. Also keep in mind that if the boat is built / brought into excistence prior to june 2008 ce will not be applicable in any case.