Bartenders in the UK are going to be earning less than half of that much. The comparison to wages in the USA is not direct because we have free healthcare and other social benefits.
According to the OECD (https://stats.oecd.org/Index.aspx?DataSetCode=SHA#) the US spends about 18% of its GDP on healthcare while the UK spends about 12% of its (much lower per capita) GDP. Per captia the numbers are even more wild, the US spends about $12k per person per year while the UK spends about $4000.
While the UK could (and in my opinion should) spend rather more money on healthcare than it does, the NHS is actually spectacuarly efficient compared to the mess of private providers and insurance middlemen you have to deal with in the US.