You don't need to be an intellectual to become a commercial pilot. However 5 passes at GCSE including Maths, English and a Science are usually considered a minimum. With the over supply of pilots in the labour market airlines can become more and more picky as to what they look for. I suggest you continue to study at least two A Levels too, and pass them above a C grade ideally.
As to how you go about training do some reading on this forum.