While it is set in stone that the copper is being removed
It's not about copper removal: it's about removal of baseband voice service from the copper. Even those who remain with copper will have digital voice over VDSL or ADSL, if they choose to retain their voice service.
The PSTN switch-off will be completed by December 2025, long before most people have migrated to FTTP.
the current contingency arrangements proposed by OFCOM (back up of 1 hour) are unlikely to be the definitive resolution
That only applies to "vulnerable" customers. Others will get no support, and need to make their own backup power arrangements if they feel they need them.
People in the metropolitan areas have absolutely no concept of the problems that will be caused so often take a dismissive attitude
I didn't intend to come across as "dismissive", but there is no putting the clock back now.
On the plus side, the Shared Rural Network is currently being rolled out, which means that mobile coverage should improve substantially over the next few years. Of course, how long it works in the presence of an extended power outage will depend on what arrangements are made for backup power at the cell sites.