ok here is what i know of.
There is a little area around coughton ford in warwickshire. Also a couple of lanes in Lapworth (Tapsters / Tinkers lane). There is a good ford with island for playing on in Aston Cantlow. Some more lanes if you head from Knowle into Barston. When you enter barston keep an eye out for "unsuitable for motor vehicles" also there is a sign in barston saying "Knowle (ford)" good lane leading to the ford!
Hope this helps!