PPL 40 hours requirement, are you really ready?
With the caveat that this is based on experience mostly in the US:

Most people take 60-80 hours to get their private pilot license:
http://www.aviationcareerguide.com/private_pilot_license.asp

The harder you work, and the more often you fly, the fewer hours you'll need.  The average hours are inflated somewhat by the many pilots who run out of time or money partway through, have to stop, and must then relearn what they forgot when they start back up again.  If you have the time, money, and dedication to fly two or three times a week, you'll get your license in fewer hours (not to mention fewer days!).

Don't worry too much about the safety of it though.  Your instructor won't let you take the exam, and your examiner won't pass you, if you're not ready.

As far as flying out of a major airport, my opinion is that it doesn't much affect the time or amount of experience required.  In the US, it's usually more expensive because costs are higher at large airports, but you may not have the option.  For most pilots, the hardest part of flying into a large airport is getting lost on the taxiways - but it will not take long to learn your way around your home airport.  If anything, it will make you a better pilot.  Today much of flying is dealing with controllers and airspace rules, and if you learn at a major airport, you'll have plenty of practice with that.