Democracy doesn't work well when you're realistically only given only two options to vote for (or two and a half in the UK), and the bulk of the media is owned by a small group of extremely rich people who use their media empire to push their world view.
For a better functioning democracy we'd need to break up media monopolies to help democracy thrive on a variety of viewpoints instead of just two, and we'd need more options of people or parties to vote for.
But even still, do you think the UK would be functioning better if it was a straight up dictatorship? Looking at dictatorships around the world, it seems unlikely.
Even a very broken cruddy democracy is better than the alternative.