Planning Officers and Conservation Officers will usually find it easier to approve plans for a new or replacement conservatory if the materials used in construction are in harmony with the building it is attached too, or to those in the surrounding area.
This means using the appropriate brick or stone for plinth walls and using natural materials for the conservatory construction rather than uPVC. Timber is often looked on favourably and conservatories constructed in oak do look fantastic in many conservation areas. You may need to paint the exterior to match window frames and doors on your own property, but often it can be allowed to weather and gradually blend in with the area.
Conservatories built using glass rather than polycarbonate sheets for the roof can also be more acceptable.
Finally, great care needs to be taken when choosing the other roof materials, such as cappings, crestings and finials. You can find out more about these at Roof Materials.