You can access 1871, 1881, 1891 1901 census for a pay per view fee, free search, at www.nationalarchives.gov.uk

Once you click the link you are taken to an ancestry.com and national archive page from which to start your search.

I think the fee is similar to the cost of the 1901 census when it went online. You do not have to pay an annual/quarterly subscription to get your info.

The 1861 census is gradually coming online at www.1837online.com which again is a pay per view. At the moment only 5 southern counties are online but more are being added in April 05.