Sounds like you have the perfect opportunity. Remember this is a total guess but there could be a series of small faults - i can't tell if it's possible but after looking for splits and how they're moving under pressure having access from underneath would definitely help
Yes, the ceilings are all artex, ripping it out from underneath gives an excuse to get it replastered but also turn nailing down a riser and filling a gap in to a big job lol
Sounds like you have the perfect opportunity. Remember this is a total guess but there could be a series of small faults - i can't tell if it's possible but after looking for splits and how they're moving under pressure having access from underneath would definitely help