The form to request information from the 1911 Census can be found on the National Archives website here.
Advice on completing the form
To submit a request you must know the full address, including the street address (with house name or number), the civil parish, and the county. (See What the National Archives tell you below)
If you click the Help button alongside the 'Civil Parish' box on the form you're told that you must enter the civil parish from the list of 1911 parishes. But what if you don't know which sub-district the street was in?
We understand that the 1911 parishes are almost exactly the same as in 1901. Therefore if you have found the same household in the same street in 1901 you may already know the answer.
What the National Archives tell you
The following extract is taken from the National Archives site:
Can I get any information from the census now?
In response to the Information Commissioners decision we shall respond to individual requests for some information from the 1911 census through our existing paid search service. This service is more limited, and almost certainly a lot more expensive to you, than the online service will be. Our recommendation is that you will get much more value out of the 1911 census if you are able wait until the online service is launched.
What is the service that you are providing now?
How do I make a request now?
You will need to provide:
Requests cannot be processed without this information.
Will I have to pay for this information?
1911 Census Info is completely independent of the National Archives and the Office of National Statistics; information is provided in good faith and we cannot accept any liability for errors or omissions