Don't put too much weight on how a school handles initial enquiries and general admin. Its the quality of the one on one instruction in the air that should concern you. The availability of aircraft and the operational interity of the home airfield.
There are a number of schools I know of who are pretty shaky at picking up the phone and have nasty advertising materials yet are excellent places to learnt o pass flight tests.
Speaking to past customers if one of the most valuable things you can do. Particularly when they have left the school at least 6 months ago. When you are there or just graduated you have an understandable enthusiasm for the place you trained. Once that has worn off a disspassionate view can be gained.
If it is any comfort I can say that there are no rogue schools in the UK. If there were any that consistently did a poor job or let their students down routinely then you would hear about it here. Which you don't.
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