I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
This was flown from the Warsash side of the river. There are two car parks in Warsash, both free. The one on Shore road is by the water's edge so is often full, just do another circuit of the one wat system and go into Passage Lane car park instead. To the side of the public conveniences in the north west corner is a footpath which runs north to the ferry that crosses to Hamble and further north along the river bank into the Nature reserve.
If you do manage to park in Shore Road then head south to the open space between the sailing club and the nautical college. The foreshore along the river is Crown estate property so drone-friendly, the land, where not private is either Fareham Borough or Hampshire County Council managed.
It's twenty years since I installed tills at the Rising Sun in Shore Road but it still has a good reputation (on Google at least) so either get in there for a meal and a drink or grab an ice cream from the van in the car park
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 21/09/2020. It remains the responsibility of any pilot to check for any changes before flying at the same location.