Ok, well I'm on the Edexcel exam board and taking the last year of the old style AS/A2 exams.
In the first year we did UK Politics, looking at the Constitution, Cabinet and Prime Minister, also Judges (but we didn't do that). Then we looked at Pressure Groups, Political Parties, Democracy and political participation. There were two exams with shorter 10 mark questions (I think?) and longer 40 mark questions.
In the second year you do two exams but have the choice over what topics to do, such as US, global or European politics. I think you can do two different or two similar ones. This year we have done US politics for both exams, similar to last year topic wise, so far have done Constitution, President, Congress and Supreme Court. Other exam I think is elections, political parties and racial and ethical politics.