Partial flat roof replacement and new pitched roof

Replace original mastic asphalt which is in excess of 50 years old and has been repaired almost annually over the last few years. This is now beyond economic repair. We want to take the opportunity to replace it with a low pitch roof of trussed rafters with Decra or similar tiles, along with pvc fascias and rainwater goods. The new gable end will be infilled with pvc cladding to match. We also need to repair a flat roof over the church entrance and corridor. As the leak has damaged the an interneal wall, mew plaster is required as well as internal decoration of one room.