Absolutely agree! At 17 you won't really know what you want to do with your life, I certainly didn't and flying would be a VERY expensive mistake if you decided you didn't want to do it after all!
Add to that the life experience of going to Uni (and especially the experiences you'll have in one of the military units, which is about all I did at uni - spent almost as much time at mine as I spent on my course!), and it is a very sad thing to miss out on.
Yes, it's expensive, but the repayments are designed to be affordable - I certainly find that they are - and maybe you WILL decide that you still want to fly. But the time you'll spend at uni will ground you as a person and give you a second option for if flying doesn't work out, or if it hits hard times again! I have never though for a second that I'd have preferred to go straight into flying from school.
I also went through my training with a number of people who had been to uni and several who hadn't - the difference is vast. (Generally) More maturity, importantly, plenty of things to talk about at interviews that aren't just 'well, when I learned to fly x happened' (as long as you get into extra curricular stuff), and an ability, I found, to more easily settle into the course which isn't easy and certainly doesn't allow the same experience as going to uni.
I always feel that people who didn't go to uni missed a treat, it's a shame it's getting so expensive now but do whatever you can if you have to, I was in a military cadet unit and had a weekend job to help grease the wheels, and had an amazing 3 years that I would repeat tomorrow if I could- one that you can't go back and have at a later date.
It may also not be a bad idea to even take a year out to earn some dough before you start a degree as I did...
PS - I honestly don't think that just getting a job for 3 years instead will give you the same life experience..it'll give you more money but you're still missing the major personal development side of uni, if you ask me.
Promise I don't work for UCAS.