Do you know the height of the roof in metres? If it’s a self-erection (oo-er), make sure you’ve got space for the outriggers and don’t have it up in high winds. Obvious stuff but I’ve seen normal scaffold come down when it’s squashed up against a house and not braced properly.
That's not unusual. Lots of leaks until materials swell and close the gaps. Then you get another spate around Christmas when the wind really picks up and you get some heavy rain and icy mornings taking out mortar.
A portable aluminium tower (if high enough) would be cheaper but sounds like you’ll have an issue with space/surface for that too.