I think the initial messaging was extreme foreboding to make people realise how serious it was, but also relied on the public (and the Police) to exercise some common sense which was sadly lacking.
As an NHS worker, I feel the 'protect the NHS' one was damaging and led to far too many people feeling like they shouldn't bother the NHS with their serious health problems as they had the idea that the entire NHS was on its knees dealing with covid when many areas had virtually empty hospitals for months on end and experienced crisis points later in the year towards winter when most people were generally annoyed by lockdowns, over it, doing what they wanted and thinking it should all be in hand by then.
Social media also played a part with the Drs/nurses in hard-hit areas making emotional pleas on FB, IG or Tiktok to everyone to stay at home (I don't agree with it), and as many people think the NHS is a monolith with everywhere experiencing the same problems when it simply is not the case, there was huge sympathy to anyone working in the NHS and the claps started.
Which of course, led to the fact that many people then 'turned' on the NHS when Drs/nurses in quiet areas were posting Tiktoks of group dances etc (which I don't think they should have done) and people were saying why are we clapping for this and on and on..
And social media including MN played a part in the initial online discourse when people with very real reasons to travel, have a family member leave their area to come stay with them with very little if no infection risk, had a health concern they needed to be checked out by GP etc were told to not be selfish Granny-killers and stay the f* home just because they might get into a very unlikely car accident on virtually empty streets and burden the NHS. When many areas of the UK had empty hospitals and the staff had very little to do.