Although bell can be reconnected within a min or two of you skilled enough
I would have let the old panel hand some how cut the plastic or something got the new back plates in and powered up may odd disconnect but it would have been quick
15min ringing you letting the kettle boil
Depends how it's all wired tho, if your going to take time you can disconnect and send power to it via a battery , otherwise as above I guess
Keep windows and doors closed that way it doesn't bother you lol
Seems the euro76 is best option although I'm don't know much about it, ion 10 is pointless if you need expanders and wireless bits to add on later
You will end up taking the ion 10 out
Wireless is not an issue if you know what to do with it as above mesh systems make this problem mostly a thing of past
Lol ok as if saying I am in London is really going to effect anyone
On a side note , your not asking for anything DIY above , so the convo is an overkill
Just get quotes in and get an alarm fitted (but stay away from risco)