Buy the relevant maps and look for the byways, then check with local authority RoW. You won't find peeps posting grid refs and route details on an open forum and certainly not for folks they don't know. Have you done much/any laning?
Trust me on this, it doesn't matter what motor you drive, you may be lifted, gifted and ready to go but if you have all the gear and no idea you will get in to serious trouble.
I wouldn't want to be out on most lanes round here at the moment, too wet meaning 1- you'll damage the byways that aren't hard surfaced(rock/stone). 2 - high probability of sliding where you really don't want to be with no easy recovery possible.
3 - Places where there is flowing water will be deeper and faster flowing than normal.
Just be patient, watch the forum and if folks are going out and about ask to join - if you're not experienced driving on byways make sure you make that clear, as a friend of mine on here has in his sig, you can bull**** a lot in life but you can't bull**** experience.
I'm not having a go but you really need to know how it is. I'm sure like most of us here, once you have been out a couple of times you will be hooked but learn to do it the right way. HTH