there is access to Horbury SF by crossing the river near the Navigation pub.
follow the road north past the navigation pub and after 100 yards at the end of the road there is an enclosed public walkway slung below the live railway bridge. At the end of the walkway head west towards the SF
 
Had 25+ crossbill yesterday in a flock in an area south of Huddersfield. As they will be breeding shortly and were showing signs of pairing I have left out the location which I think is in line with the forum
 
Regards
Jim Hodson

Another way, and I find much easier for parking, is to go along the A642 past Horbury Bridge onto Southfield Lane, still part of A642, and take right turn down Daw Lane, continue right down Mill Field Road to indutrial estate at end. Go to far right hand corner of large parking lot and park. You are now just a yard or so from the river footpath.
Good directions on Google Maps.