You would have to study medicine as a neurologist is a doctor. So you would have to go to medical school which is 5 or 6 years, then you work as a junior doctor for 2 years, and then you specialise into neurology which probably takes between 5 and 8 years (I'm not sure exactly you could contact the Royal College of Physicians). But remember during your specialist training you would be a neurologist, you just wouldn't be a consultant yet. Alternatively you could do a neuroscience bachelors and then graduate entry medicine (GEM) but this would take even longer (7 years at uni total) and GEM is incredibly competitive, even more so than undergrad medicine, not to mention much more expensive.