Architectural drawings to support planning app

We want to convert our 1987-built (but grade ll listed) thatched barn into a usable annexe. We have a full set of the 1987 architectural drawings of each elevation available and a clear idea of what we want to achieve. What we need is an architect (preferably with experience of what's permissible for grade ll listed barns in Uttlesford and some energy efficient ideas). Can we put in a woodburner? Photos and diagrams available to help