The Department has published guidance to support all schools as they prepare for the return of all pupils from the beginning of the autumn term: https://www.gov.uk/government/publications/actions-for-schools-during-the-coronavirus-outbreak/guidance-for-full-opening-schools.
The guidance provides schools with advice about how to minimise the risk of transmission of COVID-19 in schools. It also sets out how the department expects schools to operate, and where there is flexibility. For boarding schools the guidance encourages schools to keep children in their class groups, but also allows for the mixing of pupils in different groups residentially and during the school day.
Boarding schools will still need to meet the national minimum standards to safeguard and protect the children in their care and those that are independent schools will need to comply with the independent school standards.