Just an update, I hit a shallow pothole slowly enough that it didn't wreck my wheel, tire or alignment, but jarred the car just enough to actually somehow unclog the **** thing. Now, I can clearly see that AC water is draining out normally and I don't get the dripping water from under the dash anymore. I found that the AC drain is a white plastic pipe concealed behind a heat shield over the exhaust tunnel (the heat shield has to be bent out of the way), almost directly under the front end of the driver's seat rail or directly under where the driver's left knee would be. I'm not sure if the layout is inverted in the left hand drive cars.. probably is, if the HVAC layout diagrams in the shop manual is anything to go by. It'll probably clog again in future, so I'm making a note of it.