[dvboy]

What about Channel 5? I assume they'll also do something.

Well, as long as they aren’t showing The Emoji “Movie” like they during Elizabeth II’s funeral, they should be fine…

During the Coronation itself on Saturday daytime
Channel 4: Simpsons x2, the movie Aliens in the Attic at 9:15, 5 more episodes of Simpsons, live Formula E from Monaco at 13:30. The evening schedule is showing TBC but imagine that's where the aforementioned programmes will be.
Channel 5: Children's programmes, until 10:30, Friends x4, the movie Sing at 12:30. There doesn't seem to be any special programming later in the day.

Sky's Coronation coverage will be simulcast on Sky Showcase.

On BBC radio, only 3 and 4 have special programmes covering events. All of the other BBC networks seem to be doing their usual thing for a Saturday although there is a gap in 5 Live's schedule.
Radio 3 from 9:00 seems to be focused on the music from Westminster Abbey and is presented by Katie Derham.
Radio 4's coverage starts at 10:00.