Some people use Landrangers some people use explorers - personally I use Landrangers when out and about but a combination of the 2 when researching stuff at home.
Don't expect to be able to look at an OS map and go straight out and drive stuff though, you still need to check them on trailwise in case they have been closed (TRO'd) or are unsuitable for your vehicle, or some have narrow gates not suitable for 4x4s etc
Can I suggest you ask general questions like this in the green laning section (where you will find lots of info too) it will save the moderators moving the post later.