I can only tell you what happened last time. I'm hoping that it is the same this time!
When I go to Far Coley I exit the M6 at J13 and follow the signs for Shugborough Hall (brown signs). Follwing the signs you eventually leave Stafford, there is a pub on the left and a substantial green area on the right (you cross a small roundabout). Just past the green area there is a left hand turn into Shugborough Hall. That's the one we used in 2008.
See you there (hopefully)