Thanks for the comments. Honestly it is not that difficult - if you can cut plastic in a straight line then you are good to go!
Got some more done on the great hall. Glued the walls together and cut out the roof panels. These are dry fitted to check. They will be covered with Slater plasticard tiles to finish them off.

A shot to show scale with a 28 mm figure.

And mock up of a castle - long and thin this one.

I have another wall piece to make up then the final three story keep.