Knowing what I know now, I would recommend going with a school who gives a better service, even if it means a higher cost.
Some schools out there have better instructors than others, but you need quality training when doing your CPL. Make sure your training is structured, and I mean make sure the instructor knows your strengths weaknesses and concentrates on the necessary items. Also, don't let your instructor use you as a taxi service whilst doing CPL training. You are paying a lot of money per hour so get maximum value!