Hope it goes ok. This is of course the perfect demonstration of the wisdom of Cain's advice to whip the plugs out on an annual basis to ensure they don't seize up.
Ford engines seem to be slightly prone to this, the sealing around the plugs does seem to be less than perfect. On my Ecotec engine (Spanner Juggler reckons it comes from a Bedford Beagle) the coil pack completely covers and seals the spark plug wells, so no water can get in.
