DON'T do the one-lesson-every-other-week thing. While I am sure there are some highly competent people out there who learned to fly that way, this approach simply is not conducive to properly learning anything, let alone flying an a/c.
Well, I don't agree entirely. Having a flying lesson is great fun. If you save up and buy yourself a lesson every time you have enough money for it, you'll have a great time anyway. You just have to consider it a bonus if at some point in time the instructor lets you go solo, x-country solo or signs you out for the flight test. But if you do it that way do not expect that you'll have your PPL after 45 hours.
Oh, and every time you fly with an instructor you can take a passenger too (in the back) and actually let him/her share in the costs. The cost of an instructor is only something like one quarter of the total cost anyway, so you could even consider not aiming to do any test at all, and simply take an instructor every time you have money to burn.