Here is a great quiz from karenjs231 on angles. Remember in GCSE there are often angles questions where 1 mark is for finding the right answer and the other is for explaining why, eg stating angles in an isosceles triangle add up to 180 degrees and 2 must be equal.
http://www.fi.uu.nl/toepassingen/03015/exercise1.html
Practice your angle estimation by finding as many different ways to get the ball in the hole as possible.
This is a great tool to practice estimating angles.
http://nrich.maths.org/content/00/06/game1/StopClock.swf
