I did exactly this on my own house, misses wasn't best pleased even though we were having new Windows fitted a few months later.
Plus dont cut metal in a bathroom, did exactly this and the sparks from the metal ruined the ceramic tiles. Must be very hot so melted the glaze, it would also damage and sanitary ware like sinks and Wc's. thought this would have been a safe place just to cut some steel ducting. Lesson learned!
I never knew the sparks could cause so much damage. Many pitfalls to avoid. Thank God for this forum.
I'll be wearing scruffy old clothes, forearms will be bare though. Do you think welders gauntlets are a good idea?