A useful video that recaps the Iron Curtain and explains its effects on Germany. It mentions the Berlin Blockade too.
Linked to the video above, this video explains the fall of the Berlin Wall and the end of the USSR. The explanation is more detailed than you need, but it should give you a good understanding of the context of the fall of the wall and the USSR.
Below is a past paper for you to have a go at as an extension task. This will help with your exam technique. You should complete it under timed conditions at home. Remember its 40 mins per question, so 5 minutes for part a. Then 10-15 mins for part b. This should leave between 20 and 25 mins for part c. You need to practice your timing so that you don't run out of time in the IGCSE exam.