Hi Mick,
Have you thought about contacting property management companies, factors, and the like? They don't just manage single flats, sometimes they manage blocks of flats and even estates. Go in with some before and after pictures, they always look stunning.
Car showroom forecourts, filling stations, tennis courts, local bus stations, office car parks spring to mind too. Could you add on a lining service for the car parks - I'm sure I've seen hardware for that in screwfix or northern tools or similar.
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