I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
Just off the busy A3, Butser Ancient Farm and Chalton are signposted. The mill is the highest point around and can be approached by one of four public footpaths as shown on the Hampshire Definitive Rights of Way map. https://www.hants.gov.uk/rh/row/maps/1809.pdf
I parked in a field entrance (the field was currently stubble) at the entrance to the road leading to Butser Ancient Farm. When it is busy you could park in the Farm car park and visit the farm itself. It was an uphill walk along path 8 which I used for a TOAL point.
The windmill was well above me so I ensured that the max height was set to over 120 metres - normally I fly coastal sites so no need to worry about contours. The site can be approached from the south, nowhere has any useful parking though, you will have to tuck your vehicle on the verge.
As the mill is a provate residence it is probably best not to approach too closely.
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 17/01/2022. It remains the responsibility of any pilot to check for any changes before flying at the same location.