Dreaded wet footwell :(

[Jingo]

Noticed the driver's footwell was wet a week or so ago and have been trying to dry it out to establish whether it was a weather or aircon issue. Having gone out to it tonight, the towel I'd put down was saturated, so I'm guessing it's rain related.

From what I've read, it's either the plenum chamber or the sunroof drain which needs clearing/fixing. My question is, where the hell are they?!

The black cover under the wipers seems to wrap around the metal bodywork, so I don't know if that needs removing or not as it doesn't seem to give any additional access. Does it vary dependent on the year of the car (mine's a '10 plate)?

I'm hoping it's an easy fix, but really can't find anything definitive that seems to relate to the layout of my engine bay.

Don't even know where to start with the sunroof drain

ETA: I've just been to look at the sunroof, and with it fully open the internal rubbers are all bone dry along with the holes on the front left and right corners, so I don't *think* it's the sunroof