It’s now possible to find all of the publicly available UK census online. You will only be find records from 1841-1911 as there is a law which protects census records for 100 years.
The best websites for finding and viewing these records are:
Find My Past – FMP is my personal favourite for pretty much all UK genealogy records. Searching is easy and you get relevant matches to your queries. It’s also possible to download images of census returns so you can save them on your computer for future reference. FMP has the England, Scotland & Wales census records from 1841-1901, plus England & Wales from 1911.
The 1939 Register is now available.It provides valuable information about 41 million people living in England and Wales at the start of World War Two.
The 1939 Register is a fantastic resource for family history and social history research as it is the only surviving record of the population between 1921 and 1951. This is because the 1931 census was destroyed and one was not taken in 1941.
You can access the records as part of a subscription at the following Find My Past websites. It’s also possible to buy credits to view the register.
Early British Census – The Early British Census (EBC) project brings the numerous disparate pre-1841 census records into one searchable database. The project offers valuable insight into household and occupational structures of early industrial Britain.
Genes Reunited – I started my own family history research on this website. They have great coverage of the UK census, plus you can build your family tree online. There’s also a community where you can ask questions about your research and get quick answers.
Scotland’s People – As far as I know, this is the only place you can search and view the complete 1841-1911 Scottish census online.
Roots Ireland – Has some census and census substitute records.
Free Census records
FreeCEN – Yes, it’s really free. It includes records from 1841-1891 (England, Wales and Scotland).
Census of Ireland 1901/1911 – The National Archives of Ireland have made available the 1901 & 1911 Irish census free of charge.
Graham Maxwell – Some free Scottish censuses from 1841-1861.