The British government has published its future requirements for products under the CPR when sold in the UK:https://www.gov.uk/guidance/construction-products-regulation-from-1-january-2021
General advice on using the UKCA mark was also published: https://www.gov.uk/guidance/using-the-ukca-mark-from-1-january-2021
It appears that anything for which you now have to apply the CE-mark under a harmonised standard will also need the UKCA mark as of January 2022. So you have 15 months to get everything ready. Only laboratories present in the UK can help with this process.
We have also been informed that the FIA, BSIA and others have already written to the UK government on this subject. The position of the UK industry is that 15 months is not long enough and should be 3 years minimum.