The not less than 500ft from a person, vehicle or structure, pretty much excludes all of the UK from flight below 500ft.
When doing low level flight for my PPL, the only place we could use was over water of the Dee Estuary, and even then we had to zoom climb over a pleasure boat.
I don't see how they can deliver parcels to any place without at least 600ft of 'runway', unless they intend to drop the goods into the back yards by parachute.
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