Dalby Forest was declared open under the 'Right to Roam legislation' (The Countryside Rights of Way Act), so unless any bit is shut for maintenance, you can go anywhere you would like.
Every 2 or 300 yards the Forestry Commission have stone roads, and these can make a uzseful easy walk. Just watch out for cyclists zooming around.
Some useful publications have interesting walks in and around the Forest. Your lodge will have a book of them to try.