This is quite the generalization, equivalent to saying that Americans love the Democratic Party. A poll in 2019 found that satisfaction with the NHS hit an eleven year low, with 53% of respondents satisfied with services in the year prior.
There's a difference between being satisfied with the healthcare it provides and loving the NHS. People in the UK love the NHS as a concept and an institution, even if we're still often critical of the quality of service provided. Additionally most people lay the blame for that quality on underfunding from the government. The NHS is largely believed to be doing a decent job with the resources is has and has been screwed over by austerity again and again.
As far as I know it was a genuinely grassroots initiative, started by Dutch Londoner, after a similar phenomenon in the Netherlands (which I think followed from Italy).
This looks very orwellian. Does it come from a grass root initiative, or was it started by the government?