It's not just the British.
For decades in the US, school administrators have been obsessed with monitoring student's online activity and email. There is a lucrative industry providing what amounts to glue and regexs for detecting and reporting suicidal language, threats of violence, and so on (you can be sure there's detection of LGBTQ language for all the various religious schools.)
There is a subreddit for K-12 IT administrators and the stuff people would post there about monitoring students was pretty shocking (also, the levels of incompetence are also pretty shocking. Most of the crowd are barely competent at IT basics. People who are in charge of IT at multiple campuses.)
Tell your kids that any email account associated with the school, and anything they even type into a school device (phone, tablet, laptop, computer) is monitored, and even the most innocent keyword could flag their email and put it front of admins. If they want to talk to a trusted friend about anything regarding the administrator or teachers, or something regarding mental health, sexuality, bullying, violence, etc - they need to do it on devices not associated with the school, with no school management software installed, on non-school accounts.
In fact, they should probably never use their school accounts or devices for anything except strictly school related communication and work.
It's amazing how completely ignorant these admins are that, say, hauling a suicidal student into a meeting with administrators is just about the last fucking thing that kid needs, and yet that's exactly what was described in some posts and discussions. The only thing they care about is snooping in student's activity and covering the school's ass.