BBC bitesize - Read all the pages and test yourself with the quiz at the end. There is also a video on logic and syntax errors.

Craig and Dave - Watch videos 74 through to 80 to cover entire 2.3 subtopic

101Computing - Full of nice tasks that help with revision

Exam question walkthrough - For the questions on 2.3, do all the questions in this video from q1 up to (and including) q9

End of topic test - A test that covers all of 2.3