Under Lockdown 3 regulations from 6th January, in England people can only leave home for work purposes if it is not reasonably possible to work from home.
Up to 5th January that was the legal position in Tier 4. In other Tiers the guidance was that everyone who can work from home should do so. However, this is now once again a legal requirement throughout England. Government guidance for the lockdown is at National lockdown: Stay at Home (gov.uk).
Also from 6th January, the clinically extremely vulnerable are advised (gov.uk) not to go into the workplace, even if they cannot work from home.
Those who are clinically extremely vulnerable, as well as others who qualify, might be put on furlough under the Coronavirus Job Retention Scheme which has now been extended until the end of April 2021, with the government paying up to 80% of wages of furloughed staff.
More on our Coronavirus (COVID-19) page, including: