the missus just drove my GT home and the clutch pedal just gave way (and is now firmly pushed against the floor)
Is this likely to be the clutch cable?

HELP!!
and If so approximate repair price please

Not much info,
What year of car, p10 or p11?
If it is a p10 i would check the cable at the gearbox, you should see the cable from the top if you look down by the battery. Have seem loads brake there. not sure on the price of the cable.