clutch cables

iv`e just had a new clutch cable fitted on my rover 220 coupe,howver it`s to slack and the clutch travels to the floor and won`t engage,iv` been told that the cables are self tensioning but i don`t believe that,is there some way to tighten the cable from the pedal end,the supposed play on the pedal is supposed to be 1/2 inch,but it`s way to much at the moment