EU GDPR will no longer apply directly to UK businesses after the transition period (January 2021). However, in spite of this, UK organisations will still have to comply with its requirements beyond 2020.
This is because the DPA 2018 enacts the EU GDPR’s requirements into UK law, meaning that functionally we will have ‘UK GDPR’. Functionally, there is very little difference between the ‘UK GDPR’ and existing ‘EU GDPR’. Those already complying with the former will simply have to persist with their current business practices.
Full article: How GDPR will be impacted by Brexit | TechRadar