The benefit of conducting a survey when it is raining is that you can often see where the leaks are.
Here there are stains on the garage roof timbers, and to the rear the gutter is overspilling down the wall.
Reroofing is needed. The roofing sheets and downpipe are made of cement asbestos, a potentially hazardous material. A licensed asbestos removal contractor will have to be employed for this work, which will add to the cost.