With the clutch all the way in, the car tries to move forward (as if you were slipping the clutch) on its own?
if so, possible bad throw out bearing (still requires cluth removal)
Start by checking your shift cables under the boot (interior), under the car, running from even with the boot, forward to the tranny.,and at the bellhousing (top rear of housing...)
make sure that they move freely at the bellhousing (have a friend row through the gears and watch them... both should move..)
FWIW: clutch replacement can vary (cost of living, location, etc) and cost up to $800..or more. (parts, labor, complete)
expect to pay at least 600. anything less, and I would be suspect of the quality..
Ray