Horse riding is generally only permitted along The National Trail within the park, which basically follows the Macleay River from Georges Junction to Kunderang Brook, then follows Kunderang Brook to Youdales, then along West Youdales Trail to the Racecourse Trail.
The route along Kunderang Brook follows a corridor between two wilderness areas, so horse riders must stay on the designated trail. Huts at Left Hand and Middle Yards are managed for their cultural heritage value, but are available for use whilst on the national trail. Horses are not permitted at Kunderang East.
This route generally takes at least 4 days, and can be impassable after rain check with Armidale or Walcha NPWS for details
Although we can't vouch for the accuracy of the information, you might find these websites useful: