Hey,
There are always questions about carrying on with education or carry out pilot training straight away. The thing is though, if you look at most flying schools and airlines, they require you to have at least 2 A levels so I think you would have to go to college anyway! The knowledge of physics and Maths at GCSE level, to me, are simply not high enough for ATPL ground school. Of course, you may have more knowledge but try getting your head around gyros!!
Never under estimate the ground school element!!
Also, although I am 20, I know I don't have enough life exprience to be a true professional pilot, let alone 17. I am not saying you're not a mature person but you may not have the life exprience airlines are requiring.
Ultimately, I suggest carrying on with education and at least when you have graduated, your qualifications would out weigh many others.