well, one thing leads to another, now the rear sill has been removed and resealed and replaced, the rear door strengthened and replaced after all the wood was rotten around it. Persisting down with rain and the water is still coming in the roof. Bought new corner sink. Can’t fit yet.
 
The roof, though has had some damage seems dry, so we will just make sure everything else is sealed on the outside and cap it with the PVC walling. Looking to get a wet-room look to the inside.

Started to fit the walling below, easy to cut, will aim at bonding it to the walls primarily, screw (capped) if needs be. We will also PVC cap the inside of the door, with a drip bar at the bottom.
(white PVC covered in blue protective film for now. The ceiling and the wall behind the toilet will be one complete sheet which will curve into the existing roof and negate any issues with leaky seals hopefully.

Going corner sink and small cupboard instead of the original set up.

All walls covered, just got to fit furniture and then mastic everything!