Gitch
how many of these are you going to sell?
There are exemptions for low volume items (I think 10 or less)
if you are just supplying them as a kit, then it's not considered a product and the responsiblitiy for all aspects of compliance falls to the constructor. My you, constructors buying kits are not subjct to the same level of scrutiny as commercial products.
What aspect of C tick do you think you need to meet? There are both safety and RFI standards that may apply.
You also cannot get permission to apply C Tick unless you are a registered business. Are you?
Unless you are goiing into a commercial venture where you will be selling lots of these, it's not necessary
Robert