Welcome from the Manchester folks.
You would be best served seeking to contact your local Groups for such knowledge as the situation regarding legal access is very fluid.
Unfortunately there is no central database of lanes on this site but with your membership comes comes access to the internet site Trailwise which tries to keep abreast of the condition and legality of the various lanes throughout the country.
You need an access code which can be obtained from the TRF membership secretary. Take a look at;
http://www.trailwise.org.ukTTFN
Hugh.