Came across this website earlier today.
http://bywaymap.com
Looks like it's still very much work in progress as it would appear 100's of lanes are missing and it should in no way be used to confirm that a lane can be driven as it shows lanes I know have permanent TRO's as BOAT's, but it's a good start and could prove to become an excellent aid for planning days out.
Please remember to refer to local/county councils or highway authorities for current TRO information before you set out