So I have cut out the floors and have found a lot of rust in the heater channels (to be expected, it's a VW after all) and some in other places.
Hopefully before to long I have it all fixed.
Here are some pics
Where the body mounts to the pan
Passenger side heater channel
Behind the battery tray, passenger side.
Behind the batter tray, drivers side
Passenger side heater channel
Again
Body mount again
Passenger side again, it's worse than the drivers
Well I'm going to source new parts and get to it, I'll post more when I have more.