If you are applying to become a British citizen, you will have to prove your knowledge of the English language, which can be achieved by obtaining a ESOL qualification at Entry Level 3. ESOL courses are regularly run at BUCFP, where you can prepare to gain this qualification.
Another requirement of the Home Office is that you pass the “Life in the UK test”, which will test your knowledge of the British life, its customs and traditions. The test comprises of 24 questions and you are required to answer 75% of them correctly. More information about the test and study materials can be found here.
Free practice tests are available at Life In The UK Test Web.