The full text of the UK's Recreational Craft Regulations (RCR) can be found here. Technically, RCR and the EU's Recreational Craft Directive (RCD) are the same.
The harmonised EU standards for recreational craft are now referred to in the UK as "designated standards". Both are identical in content. The "Designated Standards" used under the RCR are published here by the UK government.
After 31 December 2021, manufacturers shall register their Manufacturers Identity Code (MIC) with the UK Register in order to place craft on the UK market. It would be better to get this underway much earlier. The UK MIC register is managed by British Marine on behalf of the UK government. To register a new MIC, follow this link.
However, watercraft with an MIC issued in the UK can no longer be placed on the EU market and their manufacturers should obtain a new code from the authority of an EU Member State. IMCI (UK) and IMCI are happy to assist with this.