The Vicar very kindly agreed to me taking photographs and measurements. I've taken a few so as to start thinking about how to model it but will need to return to take a lot more.
I thought about embossed sheets for the stonework but there is nothing suitable on the market so produced a very, very roughly cut and executed sample of three possible alternatives - DAS and scribed styrene, all DAS or all scribed styrene.
I've settled on the left hand one - DAS and scribed styrene. I would have gone for all DAS but just do not feel confident enough to model the whole church that way. Cowardly I know but I'm far more confident using styrene strip to model any ornamentation. Looking forward to this project.