Just cured this last week.
There are 2 access panels in the scuttle for the wiper linkage to accomodate both left and right hand drive configurations.
Mine was leaking at the nearside one just above the fan intake which then ran straight through and down the nearside heating tracts for the front and rear footwells.
Access as follows:
Remove bonnet then hinges (the plastic trim below can't get past the hinges)
Remove wipers
Remove plastic trim that runs along the base of the windscreen
You now have access to the 2 linkage access covers.
Unscrew the 4 phillips screws from each, clean the mating surfaces and apply a bead of silicon sealant (i used Wynns engine gasket which comes in a useful pressurised can)
Next morning after a rainy night i still had a dry footwell for the first time!
*When removing the wipers this can be done with controlled hits if you know what you're doing and don't have a puller/removal tool. You CAN break the plastic supports for the spindles if you're too aggresive. Hit at the ring of the wiper arm as sideways as possible while applying downward pressure at the hinge .
*The plastic trim around the base of the windscreen has a phillips screw in the centre and two plastic plunger clips one at each side. These are inconspicuous and you lever the plunger out with a small flat screwdriver.
*When i has the plastic trim off i resecured the rubber seal that was half hanging off it back on with more liquid gasket
Hope this helps you all