I’m not sure exactly how the latest information was issued
Other countries do give periodic reminders that this is common sense stuff to have lying around in case of any issues.
I would particularly say water, because parts of Essex and Kent were without water for five days in the thick of a heatwave so do please bear in mind that you need water for basics like flushing the toilet! Strangely, when I was living in London, there were a few issues with my particular street having both water issues and electric outages. There was emergency backup lighting in my block of flats, but the one I’m in now doesn’t have it.
I don’t know what in particular inspired our government to say it. It does get said periodically though, doesn’t it? Usually before winter.
in a small flat, there is a limit to what I can keep, but I do try and keep what I can.