Set off from the Infimary, down through the main gates to Haigh Hall off the main road.
Tarmac'd down to the bottom, over the bridge, then left and along the side of the river, sand and then its brick/cobbles/mud. Follow the track up, and it brings you back out further up the footpath. You can work your way to Haigh Hall almost all the way on the brick/cobble/mud tracks.
Then go past the hall, and down the access road, take a left and it takes you down a gravel access road, over the canal. Then theres a mud track under the railway and takes you close to the RUFC. You can loop back round and head back up to the hall for some extra climbing.
http://www.endomondo.com/workouts/h84Nxl2N2Qc
Its not that technical, but the climb up is moderately steep, steeper than the trail centres I have been to, so it works well as practice for there. You can do some small jumps and there are some steps and stuff too you can work in. I have seen some quite big drops/steep slopes that some other riders have used, but seem a bit too big for me.