i would take a close look at the fuse board to see if theres any water ingress??? also take a look at the fuse board under the bonnet, also check the main relays are working correctly. aircon, yep sounds like youve got a leak somewhere(no 5hit sherlock)do a search n here for info about air con in general,there are various elements that tend to fail,only you can decide how deep your pockets are,sometimes it can be very expensive to a/find and b/fix. sounds like you need a new brake switch(info in faqs in tech section on how to replace)also i found the cheapest place to buy was vw,approx 8 quid,fords wanted nearly 20 quid. i think the glow plug light is connected to the brake switch,so you hopefully sort 2 probs out in 1. booster heater,youve said its been checked?but have the fault codes been cleared,iirc if not then it wont fire up,there is a small thread on here about booster heaters,if you go ahead and read it ALLOW A FEW HOURS.war and peace isnt as long. hth a bit.