I did an off-road course last weekend organised by the Surrey TRF. It was held at Headley Park Farm near Tadworth. They have set up an area with a bit of everything including dirty great jump ramps for if you are suitably inclined, (suicidal) also big logs/tyres etc for more trials type stuff. You can use the place for £15 per day. You just need to phone first to make sure it's ok. If you want the number PM me. No noisy pipes there I think as it is a horsey place and it frightens them.