I agree with Bug Speeds post above.
In today's day, more and more pilots are coming out of flight training with a degree of some sort in any field, therefore airlines are not giving as much thought to the GCSE's as much any more.
Its always good to have a back up plan should that medical ever be taken away and a degree in a non aviation based subject would also give you a little more exposure to the rest of the world, which could work to your benefit during an interview.