Note that many of the actions in this area will also protect your own employees and that helps you maintain good service to clients.
The COVID-19 virus is spread by close (within 3 metres) contact with someone who is infected. People can be infected without symptoms and still spread the virus. When people meet there is a risk that they may unwittingly spread the virus.
The NHS desperately needs to flatten the curve of infections and hospitalisations. Without that people will die unnecessarily due to inability to get the correct medical treatment.