Fermyn Woods Country Park has set up 8 orienteering routes within the park and surrounding woodland. The routes have been devised by Leicester Orienteering Club and I am told that the longest one should take around an hour to complete. Two of the routes are also wheelchair accessible. According to Pete the Ranger, you don't necessarily need a compass,just a good sense of direction (that's me doomed then...) Maps cost £2 from the Skylark Cafe.
http://www.northamptonshire.gov.uk/en/councilservices/leisure/countryside/pages/fermyn.aspx