Even with free healthcare there is a gap between lifespan for rich and poor people in the UK. Rich people tend to make better use of healthcare and know what questions to ask.
Here's some newspaper articles giving some confusingly different numbers.
Fair point - as the other commenter says, just because you have free healthcare doesn't mean you have the confidence to use it, the knowledge to know what to ask, the access to exercise facilities or (and this is probably the cause of a lot of these statistics) the funds to afford a good, well-balanced diet.