Last year I borrowed some scaffolding long term, and bought some more. Helps speed building up and is safer.
Previously we used wood, piled up blocks and bricks.
We are putting on more brick arches on the groined vault, cantilevering them out so we get a bit of overhang. This space outside didn't allow us to put in our scaffolding and we have all these telephone poles from my Internet business waiting to be installed. So this is what we did. It is rock solid but will only be used for a few days.