Welcome to the club and forum mate.
Generally speaking, peeps won't post details of lanes on the forum, best bet is to either keep and eye out for any on here planning a lane day, or get yourself some OS maps and do your research! Identify the lanes then get onto the local council definitive maps and clarify them as open!
Some of the 4x4 mags do lane routes so worth having a look there, and look up GLASS (Green Lane Association) and join, then you'll be able to research stuff through their web site.
