I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission not required.
You can fly from Clifton Downs as long as you belong to either FPVUK or BMFA or hold the A2 CofC. Details of the FPVUK on the main forums.
In my TOAL position be aware if the Royal Marines Reserve Building. The downs continue to the north, but at this end you are closer to the Clifton Suspension Bridge.
Note as the River Avon is far below, you might need to be aware of your height above it.
The text under drones says (at the time of publishing)
The model aircraft must weigh 7kg or less, without its fuel. The person flying the aircraft must:
be a member of any of the 4 Civil Aviation Authority recognised model aircraft organisations, or hold a CAA A2 Certificate of Competence (A2 CofC) or a CAA General VLOS Certificate (GVC)
register with the Civil Aviation Authority and get a Flyer ID
have public liability insurance
comply with all Civil Aviation Authority regulations at all times
get prior permission from the Parks Service for drone operations outside of A1 or A2 Open category
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 26/08/2022. It remains the responsibility of any pilot to check for any changes before flying at the same location.