From the NHS:
WHAT DOES SELF-ISOLATING MEAN?
If you have been told to self-isolate, you need to stay indoors and avoid contact with other people for 14 days.
It is important to follow the advice for the whole period, even if you do not have any symptoms.
stay at home
separate yourself from other people – for example, try not to be in the same room as other people at the same time
only allow people who live with you to stay
stay in a well-ventilated room with a window that can be opened
ask friends, family members or delivery services to carry out errands for you, such as getting groceries, medicines or other shopping make sure you tell delivery drivers to leave items outside for collection if you order online clean toilets and bathrooms regularly think about a bathroom rota if a separate bathroom is not available, with the isolated person using the facilities last, before thoroughly cleaning the bathroom themselves use separate towels from anyone else in the household wash crockery and utensils thoroughly with soap and water; dishwashers may be used to clean crockery and cutlery stay away from your pets – if unavoidable, wash your hands before and after contact
do not invite visitors to your home or allow visitors to enter
do not go to work, school or public areas
do not use public transport like buses, trains, tubes or taxis
do not share dishes, drinking glasses, cups, eating utensils, towels, bedding or other items with other people in your home