Stanmer Park in Brighton is my go to spot.
If I think back, over the years, I’ve done new drone demo days (back when the Inspire 1 was new), a drone demonstration to a Police force, several TV interviews (ITV Meridian News, IBTimes TV, and a German TV channel).
I’ve done drone training sessions, spent a happy day doing drone freestyle flying, seen a demo of a new drone from visitors from China, filmed several promotional/demonstration videos.
And I remember testing the waypoints feature on a Phantom 3 before going to Birmingham to demonstrate it for the Gadget Show.
The park is big enough that you can always find a spot away from anyone else.
There’s plenty of parking and a café too. And the views over the South Downs and the Amex Stadium are pretty special as well.
Highly recommended.