As has been said before, it really doesn't matter what your degree subject is (or indeed whether you have one at all) as long as you've shown that you're academic enough to pass the ATPLs. Yes, there were some engineering graduates in my intake but equally my colleagues had studied economics, geography & business studies. Just do a subject that you enjoy.
My company asked for either Maths & Physics A levels OR any degree. A degree is a useful fall-back in case your flying plans don't work out but not essential for the job.
It's more important to demonstrate an interest in aviation - which you can do with a UAS or a flying or gliding club. So the amount of time that you'll have left over after lectures might be more important than the subject itself!
Best of luck & enjoy the student life!
P