Find out where your local tack shops are and put adverts up in them. Search for equestrian Facebook groups and advertise it there. Maybe local paper/freeads or whatever is available locally.
if your on facebook there is a really big group called 'Hampshire Hooves' advertise on there - am sure some one would be interested. your not technically hampshire but there are quite a few from surrounding areas surry/dorset. are you selling or giving away?