There is significant national interest in Covid-19 infection and how it may affect children. There is clear and comprehensive guidance on the PHE website available here: https://www.gov.uk/government/collections/wuhan-novel-coronavirus. This is updated regularly and should be the main source of advice.
There have also been requests to PICS regarding the need for practical guidance much more specific to the management of critically ill children. In response, PICS have put together a short document with a summary of key points and flow diagrams for suspected and confirmed cases of covid-19 infection. The document also provides easily accessible links to the relevant sections of the PHE website.