Sorry, no gpx of routes, but if you’ve got an OS map of the area you can link some bits of woodland together which have some decent trails and are small enough to explore without getting too lost. You can park at either Bestwood Country Park, which has some of the best off piste tracks in the area and also has some gradient, or Burntstump Country Park for more direct access to Sansom Wood, Blidworth Woods, Watchwood, and can make your way to Harlow Wood and Thieves Wood for a cuppa at the Portland College cafe before returning, about a 15 mile loop if you go more or less direct, giving you scope to explore or nip back quickly if you run out of time. The woods are generally sandy so you’ll escape the worst of the slop of more open areas. Wish I was around to show you the best bits but I’m off to the Peak!