Alan, Bob and Johnny - thank you for your considered responses.
Alan - your response in particular was very helpful. Unfortunately, as the description is changing, I’ve been advised that a new full application would be required.
Work wouldn’t commence on the amendment until permission was granted though. The question is whether we would have to re-request CIL exemption and whether we would qualify as technically the build had already started for the amended application.
I’m sharing this thread with my architect and will also try and speak to the council.