Hey!
I took OCR Government and Politics AS - although the content of the courses may be a little different the exams are practically identical. I bought a textbook and revision guide and just memorised the content of the 3 compulsory topics which I knew could come up and the 1 uncompulsory question which I knew I wanted to answer.
Gov and Pol AS is basically about learning lists and just listen to the news once a day and you'll be fine. You can easily pick up relevant examples close to the exam.
I would advise to revise little and often though because there's quite a lot of content to learn.
Hope this helps! (I got an A by using these methods)!