Arut,
As I am on the left side of the Atlantic, I can happily declare to have no local knowledge of UK flight training. That said, there has been immense amounts written about it here, from the whole paying up front issue, through to having multiple/ wasteful/unskilled instructors. Though I'm not sure that the perfect answer is obvious, the posts raise many good issues for your consideration, prior to your making your commitment with a school.
Circulating these important concepts in you mind will probably make you a much more qualified new student, and that is to everyone's benefit, but most of all yours.
Welcome to aviation - it's amazing!