Astra H Mk5 door sill water leak fix

Bought this Astra H 55 plate for the mrs earlier this year and so far it's been a good car, a little thirsty but she loves it which gives it the thumbs up from me. So along comes winter and I volunteer to drive home but what's this all the windows have condensation on the inside. Turns out it's been doing this for some time and I knew straight away it must have a water leak. So on the drive home after much cursing and blower on full blast trying to dry the window I remember washing the car and noticing water on the passenger door still. At the time I thought I got too close with the jet wash but opening the door showed this was the problem. Water travelling along the rubber on the door sill and down the gap between the rubber and plastic then under the carpet. Top of the carpet was still dry so that was a relief that the floor matting was not soaked but I needed to fix this asap.