No, UK airlines (or the military) don't give a damn. They don't ask you for a degree in the first place, so they're hardly likely to complain about what degree you choose to do. An MSc in Underwater Basketweaving and Seaweed Preservation is fine, if that's what turns you on.
Neither will it feature greatly at interview, unless your degree is a particular interest of one of the interviewers, other than to establish that some thought went into your choice of university and course. Even if it's just that the place you chose had the best bars and a 10:1 female:male ratio.
We find ourselves repeating over and over again on this forum: your degree subject does not matter either at interview or with relevance to your ATPL exams or your later career as a pilot, with the sole exception of those tiny few who wish to be considered for test flying. For God's sake, just go to university and enjoy it, making the best use of the opportunities afforded you when you're there. The only factors in your choice of degree should be; a) what do you enjoy and; b) will it help you make a living if you don't make it as a pilot - which many of you won't.