Memorizing political vocabs and knowing their meaning can be immensely suffering, like the Cabinet and Backbenchers...(for foreign students like me) however, you said you have an interest in citizenship, and if you have a basic understanding of politics then you can pick it up. Also, if you don't mind doing active citizenship, have a go. The most important thing is to read newspapers, then naturally you will know most of the political vocabulary, which will help you answer exam questions with ease