2014 Superb Lauren +Klement estate drivers footwell water ingress, again!!

Having had the sunroof drain thoroughly cleaned / checked a few months back and with rain in between, I`d had no water in the drivers footwell for months..Yesterday after the deluge overnight, got in car to find a massive puddle on the rubber mat. I`m going to investigate behind the scuttle panel under the wiper arms, but wondered what I would actually be looking for and where once the panel is out? I`ve also seen it suggested about issues behind the wheel arch trim and again, wondered what I would be looking for once the trim is out?

Edited 3 hours ago3 hr by scubasad