School of 1250 pupils, 800 staff of whom probably 300 live on site. There is control of the kids when they're here, but between holidays, exeats and random weekends where some are allowed to go home (or behave like idiots and are sent home in disgrace for a few days) they are always in and out. Not as frequently as a day school, but on the flip side, we have a LOT more contact with them than in a day school - we live with 52 of them, DH eats 3 meals a day with our house 6 days a week - the children and I join for breakfasts and all meals on weekends, plus the house staff coming in and out daily.
Bubbling by house not possible as all lessons are across houses. Bubbling by year group also not possible as each house has all cohorts. As far as I have heard from DH and other friends, no social distancing is proposed besides enforcing handwashing and hand sanitiser at the door of every schoolroom, cancelling various school activities like choir and relaxing school uniform to some degree. There is to be no entry by parents into boarding houses in term time, but I guess they can still take their kids out for lunch...
At least we are fit and healthy. Another housemaster's wife is immunosuppressed and shielding, I know they are pretty worried but there is no feasible alternative unless she moves out.