Cowm to the north of Manchester
Hill n Ditch to the west of Manchester
Parkwood 4x4 way off to the East of Manchester
Weston Coyney to the South of Manchester
Silverdale to south is closed at the mo, but might be open again by April?
As Gemsdad says, none are IN Manchester. cowm is about 30min from centre, the others are 45-1 hour drive from centre, depending on traffic.
Parkwood 4x4/ Tong is the best organised site and feels the safest in my own view
There will be others that I haven't mentioned that I haven't been to personally, so can't comment