A-level Computing/AQA/Problem Solving, Programming, Data Representation and Practical Exercise/Skeleton code/2012 Exam
The exam questions are very hard to predict and this site is by no means going to give you everything you need for the questions you'll sit. The most important thing you should do is learn how to program, and learn how to program well!
The exam is split into 4 sections that must be completed on a computer:
Section A 
<30 minutes> Theory Questions based on the material you have covered for unit 1. For an overview of what this might include see the specification and this wikibook
Section B 
<20 minutes> Programming solutions to short problems, not based on the preliminary material or skeleton code
Section C 
<20 minutes> Theory questions about the preliminary material and skeleton code
Section D 
<50 minutes> Program solutions based around the preliminary code. The guidance below doesn't pretend to offer the actual questions that will be set in the exam, but by doing them you should hopefully get a better grasp of the code and be able to answer any questions thrown at you during the exam.