Haldon Forest Park is very well set up for walkers and mountain bikers. You can also hire a Segway or go ape on a zip line. There is a cafe, and a bike shop that hires bikes.
Families and beginning mountain bikers are very well catered for with 12km of easy trails that weave through the forest. There is a 9km intermediate trail and a short 1 kilometer advanced circuit. These are all-weather trails and they are very well sign posted. In addition there are some unmarked trails scattered around the park, including at least one challenging downhill trail. You'll spot them as you ride the official trails.