The latest recommendation is that people who have a persistent cough or a fever, should self isolate for 7 days, or until better - whichever is the longer period. Travellers, or people who have been in contact with infected people  and have symptoms should self-isolate for 14 days.
So what does it mean to self isolate? Find out when to do it, and how to do it here: https://www.gov.uk/government/publications/covid-19-stay-at-home-guidance/stay-at-home-guidance-for-people-with-confirmed-or-possible-coronavirus-covid-19-infection