Steve the fan does indeed need a transformer. Either chop up a laptop charger (any 240v to 12v will do, a fan needs less than half an amp usually and providing too many amps isn't a problem). I got one off eBay which is dedicated for £4.
The extension cord was £4 from tesco, project box £4, 40w bulb about £5, old pc fan, plastic grill £3. Few bits and bobs I had like cable ties etc. 50p for aluminium mesh. So about £30 if you needed everything? Not bad really! 24hrs in the meat is still wet. It's in the garage at about 9'c and the bulb doesn't do much. I may need to bring it inside.