DfE states;
Children and young people with COVID-19 should not attend their education setting while they are infectious. They should take an LFD test from 5 days after their symptoms started (or the day their test was taken if they did not have symptoms) followed by another one the next day. If both these tests results are negative, they should return to their educational setting if they normally attend one, as long as they feel well enough to do so and do not have a temperature. They should follow the guidance for their educational setting.
This means keep your kids with covid and symptoms at home until negative.
Luckily the school I work in have already sent this to parents as has my kids school