Not British, but I can't help but wonder if this is actually anywhere near as effective as it is restrictive. My daily routine literally wouldn't change with this. I only leave for work and for groceries almost any day of the working week. I encounter the overwhelming majority of the people I interact with in those settings, and those seemingly wouldn't be affected at all by this. I never excercise more than once a day and don't know anyone who does - seriously, how can that particular restriction possibly have any measurable impact? I don't think I'm unusual at all, I rather think I'm quite representative of most people.
If the aim is to decrease unnecessary interaction it would make more sense to simply order businesses, pubs, restaurants and other places people gather to be closed and limit the size of private events to something reasonable. Trying to micromanage when people leave their homes like this is going to be impossible to police - which has been the experience in other countries - and arguably pointless.