It pretty easy to navigate yourself around Greno woods even without any marking. Go along the top track until you find an interesting looking track, follow it until you hit fireroad, ride fireroad uphill until you are back at the top, repeat until bored/knackered/dead.
Wharncliffe on the other hand is a frustrating experience. The Red route lures in the unwary, being well signed at the start (just below the car park) and has some good bits early on. But I don’t think it was ever completed, hasn’t been maintained and much of it a horrible boggy mess. And it is very easy to get lost, or head off down a very tricky downhill. There’s some great riding in there, but I would avoid it after this much rain.