Here's a brief history of the UK Census records:
The first national census was taken in 1801 - and a census has been taken every 10 years since then (apart from 1941).
The first census to record names was taken in 1841.
All census records included details of anyone who was staying in a property on census night - including guests. So you may discover some strange names in your search!
From 1851, a person's health was recorded (often in less than flattering terms). In 1881, for example, people could be recorded as being "deaf and dumb, blind, imbecile or idiot, or lunatic".