The directions to the campsite in the Wye Valley CC Guide (1997) on page 13 are out of date (though the map on page 233 of the same book is correct). It's been corrected in the new (2007) guide if anybody has one.
Drive for 3mi past the Rising Sun pub in Woodcroft on the B4228 towards Coleford. Turn down Miss Grace Lane (an unmetalled track) on the L just before a RH bend. When we were there in 2004, there was no sign to say there was a campsite, but the road name is marked. Go straight down the lane and you eventually get to Beeches Farm, where the camping area is clearly marked.
The turn off down Miss Grace Lane is here:
http://www.streetmap.co.uk/streetmap.dll?G2M?X=355420&Y=198535&A=Y&Z=4 The track is the red dottted line continuing past Sheepcot. Beeches Farm is the group of buildings just right of the "e" in "Offa's Dyke". Note, the track shown from Madgett's Farm no longer exists.
Cold water, no showers, but £2.50 per night (in 2006).