Just stumbled on your great project... :)
I also commenced a Swindon Works "A" Shop project in O gauge ... just thought I'd share a few images to show you progress.... we both chose South West corner... but you are a little further West than me... and I incorporated the Weigh House (at least the end). Still a long way to go... My desire to create it comes from when I used to visit the works in the 80s to view the scrap lines... and the A shop always blew me away... so beautiful.