I am a diver and I would say that PADI is purely for so-called 'holiday divers' which is what you aspire to be, i suppose. PADI courses are basically a crash-course in diving. They teach you to dive in 5 days. If you want to be more serious with diving, the British Sub-Aqua Club (BSAC) is a sensible choice because 1) diving in British water (particularly the Solent) will prepare you for almost anything, the swell and temperature is a lot worse than other diveable places in the world and 2) because they teach you better, making diving safer and therefore more enjoyable. The courses are longer and you have to do your homework and learn everything.
The PADI course that I went on worried me, since there were 3 kids in my class who failed the final test, but were still given their diving card and were permitted to dive, which is life threatening, especially if they haven't a clue what to do if their arms start locking up or if they are separated from their buddy...
Basically... PADI is a good idea for holiday diving at 5 metres below the surface, but anything more serious and 20+ metres (where all the good stuff is) I would go with BSAC.