First off - keep working on your A Levels - many schemes require two or more A Level grades at C or above, with the British Airways one requiring BBC or above at A Level. The British Airways scheme could be regarded as the most foolproof, as once you have completed training you have the sum paid back to you in full over seven years, however this makes it very popular and even getting to the interviews stage can be a challenge. I'm about to start applying for the Atlantic Airways scheme, which requires no funding up front but does require you to have a PPL before applying, and costs will be paid back once a position is secured. As I have been told many times, and it is good advice, find something that makes you stand out from the crowd and do it. I'm sure that interviewers get bored of hearing the same old stuff, and having a unique or interesting hobby or interest can help grab their attention.
The fact is, this is not an easy career to get into - but don't let that stop you from having a damn good go at it. I'll be 18 a month after you, but I have the benefit of a funding source. Sometimes however, money is the least of the issue, you first have to find a scheme that you get far enough in to actually need to pay for. The other ways in which fledgling careers are started are numerous. Whether it's bush flying (something many younger wannabes seem to be getting more and more interested in) or crop spraying, it seems that aspiring airline pilots are finding even more ways to make their dreams a reality.
My advice to you? Same as many peoples advice to me. Have fun, and for this great bit of your life that exists between 18 and 21, don't let the prospect of a future career dominate. By all means, apply to every scheme you can find and fly in smaller aircraft at every opportunity just for the experience, but make sure you remember to have fun. I hate the saying with a passion, but you do only live once, and it's very difficult to do the kind of things you do at this age once you've retired (do with that as you will...)
If you have any more questions don't hesitate to ask
