The short answer is you stand little or no chance going to a modular school if your ambition is to get straight into one of the legacy airlines eg: BA. All recruitment for national/legacy airlines is through integrated courses or mentored schemes run through the likes of Oxford/FTE or CTC.
Later on once you are experienced with a few thousand hours under your belt on a relevant aircraft type then you have every chance of getting into one of the big airlines irrespective of where you trained.
Having said that.....I would be more concerned that you have formed an opinion of a school in Poland (presumably on cost alone - never EVER a good idea) based on what you have read on pprune.