Having had a looksy about, Hailsham, and betweem Maidstone and Ashford, right up to Folkstone have the largest amounts of lanes, with the biggest looking to be around 2-3 miles, however I am only going by maps and have no idea of their condition or accessability.
There is also supposed to be a very long lane near Sandwich Bay Estate which goes right through the Royal Cinque Ports golf course, bypassing a toll road.
http://www.streetmap.co.uk/map.srf?x=63 ... ate,+Kent+[City/Town/Village]&searchp=ids.srf&mapp=map.srf
We could try a suck it and see approach. I'm happy to plan a route and pick some lanes, if anyone can help with local knowledge of this area.
Keep me updated on a date. Sunday is prefered over Saturday but I'm flexible.