Yesterday evening, after school had finished for the day, the government changed the guidance for what is allowed for childcare under the new restrictions which came into force today (Tuesday 22nd September). The government has now stated that people outside of your direct bubble can provide consistent child care duties (both formal and informal arrangements) only if it relates to someone getting to work. This guidance does not allow for play dates or parties or the sharing of collecting children from school if you are able to collect them yourself.
I hope this clarifies the situation for families in light of the change of government policy yesterday evening which was announced after the email from school yesterday afternoon.