Actually we should avoid sounding like arrogant Englishmen here, Birmingham may be close to the centre of England but it is not close to the centre of Great Britain so the sensible thing would be to consider Newcastle or Durham which probably are.
However this along with the Birmingham suggestion is not sensible the reality is no airline is going to say to passengers we know you want to fly in to London but we will take you to Birmingham or Manchester which is just X hours away by train.