The walk sounds really boring, but in real life dogs can have a thoroughly good time. And it's accessible to all.  Go through the gate and just walk on the broad hard-surfaced way beside a watercourse.  There are broad swathes of grass to the side and dogs can safely run off lead and leap and frolic up and down the bank. There's just one moment by a bridge where dogs are safer out of the water.  Reach another bridge a mile or so onwards, and then turn round to return.  Ideal for anyone who dislikes following complicated directions!