It's been said on many threads before (there, got the obligatory "use the search!" in
), but you're young enough to apply for the few bursaries out there. The one run by Dennis Kenyon springs to mind, but there are a few others - have a look through the Air League website (Google will help you find it).
Don't rule out the forces until you've actually had a proper look and spoken to a few people (the military aircrew forum might be a good place to start). I will say that if you're just joining up to get free flight training, you probably won't have a great time (assuming you get in at all). Also, at least for the Army Air Corps, to go straight in as a pilot, you need to be an officer, and that usually means you need a degree (I think).
I wish I'd started out in flying at 19, as the earlier you get started, the better. Consider the USA route (if you can scrape up the cash). Good luck!