If you want to get a British Citizenship, you need to apply for it. You can apply for one from the nearest British embassy or from within the UK. The application form you need to complete will depend on your nationality and current immigration status. For more information about the application process, you can visit gov.uk. Once you submit your application, an eligibility assessment will be conducted. Once the assessment is completed, you will receive a decision letter. Acceptable documents you need to provide to the embassy include:
proof of UK residence
evidence of Good Character
evidence of residency in the UK for at least five years
passport or other documents that can prove your identity.
Once these documents are provided, you will receive an invitation to become a citizen of the United Kingdom. For more information about the requirements, you can refer to gov.uk.