Yes i used to play on those garage roofs i lived on witton rd by SH churchThere was a large square of garages but it was not at the bottom of my garden however I could see the brick wall that surrounded the garages that area has long been demolished.
the gospel hall was a small church around the corner, its still there, I only remember going there occasionally for Sunday school which I hated if the weather was nice I would be out playing so my mum could not find me it was the only way I could skip Sunday school.
I used to live at beacon hill Aston. where abouts did you live ?