I have now had a chat with the nice man at EE who is handling my mobile phone service complaint, and who will stay on the case until there is resolution.
He told me that they have had a fire in the electronics cabinet at the local 4G mast (or more properly, 'tower'). A lot of electronics have been destroyed, and it will all have to be replaced once the health and safety checks have been made, to ensure that it is safe for the engineers to do their work. It seems to me that the local 4G service won't be restored until much later this month. (Just as well I'm going away on another holiday)
Although my two-year SIM-only contract with EE finished on 27th April, and that (in their words) I am 'out of commitment', my complaints advisor has happily authorised a waiver of next month's direct debit payment of £25.01. I think that, for now, that's fair enough. So far I have suffered only some minor inconvenience, as I can use my phone for everything if I drive off to some place not far away. But it's a nuisance all the same. I can't keep reliably in touch with anybody, nor check my bank, savings or credit card accounts, to name just two of the many, many daily uses I have for my phone when at home. The odd text does get through: apparently there is still a residual 2G service in the background, although it is very sloooow.
Often my phone shows no signal bars but nevertheless a 5G icon. The man explained that there is in fact a single low-power 5G transmitter in the village, and my phone must be detecting it, although it can be for test purposes only, because at present there is no official 5G service here at all. (Good to hear about, though. Perhaps this small 5G foothold is the precursor of a full 5G service sometime)
I hope my next door neighbours will let me set up Wi-Fi calling on my phone, using their Wi-Fi (as I have none of my own). It'll only be on a 'just in case 4G ever fails' basis, and therefore wouldn't get used at all in normal circumstances. I'll feel less cut off then, especially after dark.
But I continue to think it's a waste to spend money on a new high-speed fibre-broadband installation and a contract to go with it, whatever the virtues of having an alternative to 4G. I would never get full value for money from it, partly because I'm away from home so much, and partly because I consume so very little 'home entertainment'. There are many more urgent calls on my income. Besides, I urgently need to restore my savings to what they were, and then take them forward so that one day I can address presently intractable problems such as how to afford a new car, or a new caravan, or modernise and redecorate my home.