Not sure if you've already found out about this - but apparently ASDA's already in court about this. My information's a bit patchy and may be completely untrue, but it was gained from the son of a lawyer involved, so I'm guessing it's valid.
Also, one of the CAMSFC teachers has said that the college is keeping the teachers almost completely in the dark about this, but he has been told that if the site is sold then it will be under the condition that the buildings there will not be knocked down until the other Marple campus has been renovated.