Following the announcement by the Prime Minister on Monday of his proposed road map out of lockdown, the government have produced slides detailing what is proposed at each step. These can be found here HM Govt Roadmap 2021 slides. As the Prime Minister said, these dates are provisional and should be used as a guide. If the data indicates that rates are rising again, they will not move to the next step.
For more detailed information please go to:
https://www.gov.uk/government/publications/covid-19-response-spring-2021