Nice spot Frank.
  I picked up an impact wrench gun from Argos yesterday. Works off 12v so you clip it to your car battery or similar - doesn't run off mains as it won't supply enough juice. Does upto 210Nm of torque, which should be plenty!
 Comes in a blow-moulded case with all the connectors for a cigarette lighter and croc clips for a battery along with a selection of sockets. 
 Best bit was that it's half price in the Argos sale if you can find one in stock - a snip at 9.99 !! 
 As for ebay, I found this auction rather appealing ... don't know why though!!! 
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5745308564