Thank you to everyone for your support and kind comments.
The outer surface is foam core with the outer layer of paper pealed off and brickwork scored with a pencil.
The scale is 25 / 28mm.
Will think about the moat once I have finished the castle. One of my greatest concerns is for storage of the completed work. The castle will be stored in plastic containers and can be broken down into walls and towers with the keep and gate being the largest.