I’d put €1000 this man has never even been on a roof

The roof is now tiled as normal, except the 2 tiles above the vent which need to be cut, unfortunately they now are resting on nothing but the felt and have holes at the side. You will need to cut them with outcuts and I've not got my angle grinder. Damn, forgot to fold the edges og the felt over and I didn't read the instructions, now I've wind blown water inside. Must go back on the roof and remove that mechanically fixed tiling. Fall of roof, break legs.......

Using the UB 47, how close to a vertical wall can it be positioned. Below the roof, I should like to clip the duct pipe to the wall. Does it need a flexible pipe at the end to connect to the UB47 to take it further from the wall. If it can be close to the wall, are thee any problems with the existing lead flashing or can it just be dressed above the UB47 .