how to apply British citizenship in united kingdom

Applying through the Nationality Checking Service (NCS)
The nationality checking service is provided by local authorities (for example your county council or city council). A local authority can accept and forward your application to us. They will ensure that your form is correctly completed, and they will copy your documents and return them to you. They will ensure that your application is validly submitted and that the unwaivable requirements for citizenship are met. However, they will not give you nationality advice.
This service has been very popular since its introduction in 2005 as there are a number of advantages:
last year only 2% of applications made this way were unsuccessful. This compares with 10% refusals for other applications;
you can keep hold of your documents (like your passport) - we can, however, request the originals if we need them.
Individual applications
You may apply directly without using the nationality checking service or a representative. You must submit either original documents, or a fully certified photocopy of your documents.
The application form and guide gives guidance on what documents need to be submitted and your application may be delayed if you do not submit the necessary documentation.