An update published on the UK government’s official website on 24 August 2021 states the following:

You can continue to use the CE marking for goods placed on the market in Great Britain until 1 January 2023. The UKCA marking must be used for placing goods on the market in Great Britain from 1 January 2023. The UKCA marking can be used now and we encourage businesses to start using the UKCA marking as soon as possible.

This means that it will be possible to continue to use the CE marking for goods placed on the market in Great Britain until 1 January 2023. The UKCA marking will be required for goods placed on the market in Great Britain from 1 January 2023. However, the UKCA mark can be used now and the government encourages companies to start using it as soon as possible. For more information, visit https://www.gov.uk/guidance/using-the-ukca-marking