Hi Robin,
Now this sort of leak I can help with!
Remove the plastic cover that fits over the air intake for the fan and the fan motor unit.
In each corner of the scuttle area (where all the old leaves will have gathered) you should be able to find a clear plastic tube about the thick ness of a stout ball point pen.
At the bottom of this tube there is a restrictor that is inserted into the tube. This restrictor compensates for the "bow wave" of air pressure at the base of the windscreen. It also gets glogged up and then stops the sunroof channels from draining.
Cut the bottom inch off the tube and slimey green water will pour out. Try to keep the bit that you cut off and then remove and re-insert the restrictor (after cleaning it out).
If you don't refit the restrictor it will still be fine, but you will get a "gurgling" noise when you drive in wet weather. The gurgling comes from air pressure differential between the base of the screen and the sun roof. It can be a bit tiresome when the car is wet, but it tends to lessen as you drive faster and the water is blown away.
I hope that fixes it... Mike
