I somehow managed to fix it. It involved removing plastic and metal convers under dash, unplugging the bcm and battery, pulling the loom in as much as possible through the firewall, cutting the grommet neatly being sure not to damage any more wires, undoing the electrical tape and inspecting the damage. I had 1 wire completely detached, 1 half gone and one which was just missing a little insulation. i taped up the one with the damaged insulation, and cut the half stuffed one, stripped both ends of the ones that were most damaged, twisted and turned them to reconnect and then....somehow.....i managed to solder while lying down upside down where the pedals are and then i taped them up.
Don't ask me how i pulled it off but i somehow did, and now my electrics work properly again. Depending on how badly damaged the OP's loom is, this job could turn into a complete nightmare as there is so much wiring down there. Mine was only the windscreen washer squirter and the wire that makes the wipers come on automatically when they are squirting.
Good luck to the OP. I managed to avoid a hefty repair bill. Worst case scenario is you would have to pull out most of the dash to disconnect the whole loom then pull it all through the firewall and fix it from the bay. Even worse scenario you would have to literally pull out the whole loom and replace it with another from the wreckers.
Lesson learnt- be careful when drilling through rubber grommets on the firewall and in the case of an auto VT- use the unused grommet where the clutch pedal is meant to go as a means of getting a positive amp cable to the back and not the main ignition.engine loom one!