You'll need to target the source of the moisture ingress to the car. At a guess, I'd say it's probably caused by a blockage at the bulkhead vent well because the drainage holes are blocked. If you feel confident, you can attempt to clear these yourself - the driver's manual should make it easy to locate. Otherwise, I would recommend taking it to a trustworthy garage to have the vents cleared and the pollen filter replaced.

If you need help, the Honest John Good Garage Guide lists thousands of reader-rated mechanics: good-garage-guide.honestjohn.co.uk/