I have had this
problem and have posted on it, my footwells were wet on the drivers side, I removed seat and trim and lifted up the carpet, cut out the underlay and dried it in the house for a week to make sure it was bone dry, it was soaking wet when removed.
The carpet it being put back in this weekend, but car has been condensation free since I have taken it all out.
I removed the scuttle panel and only real thing I could see was where the bonnet release cable goes through into the cabin didn't look great and also the main bung where the cabling goes into the cabin didn't look to have a great seal so I filled them in with a sealer.
My door seals dont seem to be leaking so hopefully thats all it was. Will see this weekend, if its been leaking again.
To get to the pollen filter you dont need to remove the full scuttle panel, just the cover to the right. save you alot of hassle.
The pipe going to my rear washer had also popped out, remove the rear passenger side trim in the boot and you will see the pipe.