I started mapping in Open Street Map on 16th September 2010.
I am currently expanding on the urban mapping in Chelmer Village, Chelmsford, Essex, England . I also use OSM footpaths when walking in and around Essex and add/update footpaths that I find.
I use a Garmin GPSMap 60csx and JOSM.
http://wiki.openstreetmap.org/wiki/UK_public_rights_of_way - Guidance on tagging UK public rights of way (ie footpaths)
http://osmdoc.com/en/tags/ - Usage statistics on all tags and values
Recommended Online Stores
I don't have any affiliation to these.
http://www.dash4it.co.uk - Reduced price OS maps and free postage