Public Health England
Latest Public Health England guidance:
https://www.gov.uk/government/collections/coronavirus-covid-19-list-of-guidance
Staying at home, for households with possible COVID-19 infection:
https://www.gov.uk/government/publications/covid-19-stay-at-home-guidance/stay-at-home-guidance-for-households-with-possible-coronavirus-covid-19-infection
Social distancing to protect vulnerable groups:
https://www.gov.uk/government/publications/covid-19-guidance-on-social-distancing-and-for-vulnerable-people/guidance-on-social-distancing-for-everyone-in-the-uk-and-protecting-older-people-and-vulnerable-adults