Darren,
If you ride from Edge towards Haresfield, just as you get off the A4173 after about 250m there is a wood on the right. Get in there and there are some really good trails that lead you near to Standish woods (always keep left in the forest tracking the road).
Once you get to the end you will find you are on a junction with a sign post to harefield beacon. Head that way and you will see the car park. Just beofre the car park is a gate and 2 different walking routes. Take the lower route and after a few meters it opens up into 2 / 3 trails.
All of these end up at the bike specific area at the bottom, but I normally take the lower trail on the right to get down to the bottom and then come up on the left hand one.
But once you get to the bottom head left and you will see the bike firendly area. The Cotswold way markers all lead there too.
But just have a look around as there are loads of routes that you can link together to have some fun.