I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
Castle Campbell and Dollar Glen is owned by the National Trust for Scotland, but you can TOAL out with their area at the public footpath which leaves Castle Road north-east of the castle and heads up Saddle Hill (where I've placed the pin). You can also take off from the open hillside to north and to the west of the glen (be aware your TOAL location may be above the height of the castle. There is free parking on Castle Road near the castle and a larger car park at the bottom of the Glen.
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 07/10/2020. It remains the responsibility of any pilot to check for any changes before flying at the same location.