Why not bring your own bike and cycle the South Tyne Trail !
With free carparks at both Alston* and Slaggyford you can park up and ride the trail. There are miles of permissble paths and quieter roads in the North Pennines so there are lots of routes to explore. You can even bring your bike on the train ( subject to space being available).
*Please be aware that the car park at Alston is locked when the cafe closes – check the closing time before you leave your vehicle.