As of January 5th, 2021, the Ministry of Health Protective Measure regarding the entry of persons on the territory of the Czech Republic is updated
Current conditions for travelling from the United Kingdom of Great Britain and Northern Ireland (UK) introduced as a consequence of a new covid-19 variant are further extended.
Each person travelling from the UK to the Czech Republic has to be in possession of a negative result of an antigen test or PCR test which has been performed in the UK no later than 72 hours before the departure, no matter which means of transport is used. After arrival there is an obligation to undergo PCR test at the earliest during the fifth to seventh day. Only international transport workers and persons transiting through the UK to the Czech Republic are excluded from above mentioned obligations.
You can find more information here (pdf, 346 kB).