Have you looked in to learning in the USA? If you're careful it can certainly be cheaper; you won't save loads, but you might save something and learning in a very short space of time is generally the quickest way in terms of total number of hours flown (and hours cost money).
Once you've qualified, as others have said, flying can get much much cheaper - it depends largely on what you want to fly and where you are (i.e. what group aircraft are available in your area).
Having said all that, as someone else said, if once a fortnight is the only way you can do, do it and enjoy it. But book more slots than once a fortnight otherwise the weather could dictate that you don't fly for a couple of months and that would be a pain.