I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
There is a public car park just off Bosham Lane. Make sure you check the tides, as a muddy estuary is not as attractive.
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 09/07/2021. It remains the responsibility of any pilot to check for any changes before flying at the same location.