I'm super late on this, so I'm happy to discount anything already in progress (technically, athletics, Climbing, Swimming, and Golf!).
Artistic Swimming: Do our pair finish today in the top 5? Yes
Athletics: Do we win a gold today? No
Cycling Track: Do we win a gold medal today? No
Diving: Any Brits in the top 5 of the WOMEN'S FINAL? Yes
Golf: Do any Brits get at least par for the day? No
Marathon Swimming: Any Brits in the top 10? No
Modern Pentathlon: How many Brits make the final? 1
Sport Climbing: Does ROBERTS medal? Yes