It requires an interest in current affairs, so watching the news on a daily basis and reading a broadsheet newspaper becomes a regular part of your routine, but that's not as dreadful as it probably sounds once you get into it.
One half of AS, Unit 1, covers current affairs, and things like democracy, voting, pressure groups (i.e. groups like Greenpeace who put pressure on the government to take action) and party politics, which looks at the ideologies of the three main parties, whereas Unit 2 explores the law-side of things, like constitutions, devolution etc.
It varies from exam board to exam board, but most of the content is fairly similar.
At A2 (for Edexcel at least), you choose an 'option' topic out of 4. They all cover very different parts of the subject, and although it's an option, your teacher(s) will probably pick which topic you do based on their own specialisms. We're studying Political Ideologies for Unit 3 and Unit 4 this year, because our teachers are strong at it and the majority of my class are going on to study Politics or a related discipline at university.