when either washing the car with jet wash or heavy rain, there's water dripping in the passenger side foot well, its a mk1 focus any ideas where it could be coming from?

 

Probably leaking in around the pollen filter. As far as I remember this was a common problem on the focus

 

would getting a pollen filter seal sort the problem out

 

If the pollen filter cover is damaged or the clips broken you'll need another one, I'd take the cover off, the filter out and give it a really good check and clean. When you put it all back together make sure the windscreen is spotless where the seal sticks to it and that all the clips fit properly and tightly.

Good luck