I don't know the Pooley's book so won't comment on that. however you will find that the exam is structured so that it is NOT possible to "reverse engineer" from the available answers.
The OP is right in his concern - if you are a degree or so out in measuring angles then it is possible to go wrong in the exam (its perfectly true that this needs an unrealistic degree of accuracy IMHO, but I didn't write the questions).
My tip for measuring angles accurately - do not draw lines on the chart by trying to judge where the centres of the airfield symbols are because you won't be accurate enough. Instead draw from the edge of the circle of the symbol to the edge of the circle of the other symbol (same edge of course!). Your line will be offset a bit, but the angle will be very accurate.
Also remember to measure the angle approx. half way along the track, not at one end or the other. And apply corrections for deviation etc in the proper order.
Hope that helps.