I COULD pay out about 55 pounds for a provisional driving licence, which would serve as ID. But, 55 pounds isn't far off 80ish pounds, which is how much renewing a passport costs. So I would rather spend the money on a passport, because it means I can actually leave the country if I want, and it's also good for ID, and lasts the next 10 years which means I don't have to worry about it for a long time.
The ID thing is really over the top, there ARE other types like 'Bite cards' that schools give out for free and stuff, but no place accepts them as ID, because they say they're too easy to fake.
Other than passports/provisional licences, there's no ID.