Yes, I get vaccinated every year. In addition to protecting me personally, it helps ensure that I’m not part of the path that leads to serious illness or death for others. In the US everyone is encouraged to get vaccinated, and the Affordable Care Act requires insurance policies to cover the cost. As Jan wrote, herd immunity can help protect an entire population, at least when the vaccination rates are significant. Herd immunity is remarkably effective even in years (like this one) when the efficacy of the vaccine isn’t ideal. Herd immunity doesn’t work properly if you limit the vaccine to those at risk, though.
I can’t speak to the politics or economics of the NHS, but if they are treating vaccination as a individual (rather than a population) solution they are acting like the UK is a very poor country. There is a predictable surge in flu each year, though it varies in intensity, and waiting for an epidemic to be declared is too little, too late. In addition to the direct effects of the flu, large seasonal increases crowd out ambulances, emergency departments, and hospitals, leading to additional health issues and deaths.