John Rylands is a lot closer than Kew, I might try there first, though as the map there was prepared by what became Manchester City Council I am not too hopeful of finding what I’m after, which is actually Stockport. I am guessing there is nothing in the library at Stockport as the query came from a friend who works for the council and he after it for work.

I used to work for the heritage library in Stockport. Off the top of my head I don’t know but they will definitely look for you if you send a request. There’s various photos of bomb damage in the archive there too, only a fraction is actually on the online bit.

The Stockport Air Raid Shelters? They might have something?