I need a structural Engineer

We are looking for a SE to perform some calculations on a loft conversion design for a bungalow. The design included full height (2.5m) dormers with low pitch roofs on both front and rear elevations. The existing roof is a purlin design with a ridge board (150 x 25). We anticipate that a additional flitch beam will be required under the existing ridge board. We will then need further flitch beams to provide the ridge on the new dormers. Each dormer is around 4.5m wide and 3.5m deep (Ridge to eaves).