There is no requirement for any pilot to have studied Maths beyond GCSE level, let alone have studied Engineering of any sort at University. The suggestion that degree-level maths or engineering is particularly attractive to airlines is a fallacy; a myth propounded mainly by Wannabes who substitute poorly-informed logic for knowledge.
There is no requirement for any pilot to have studied anything at degree level, though having a degree may make you more attractive if you are attempting to get a sponsorship. However, none of the sponsorship programmes demand any higher qualification than A-level. If you decide that you wish to take a degree, do it in a subject you are sure you will be able to maintain your entusiasm for, and interest in, for the three years of the course. It would also be an idea to study a subject which may lead to an alternative career if flying doesn't work out - but then, as has often been pointed out before, you may be better off learning plumbing or bricklaying.
So, what qualifications does a pilot need? Almost all the employers that operate sponsorships require 5 GCSEs at Grade C or above (to include Maths and English Language), and two A2s in 'mainstream' subjects. If you're not going for a sponsorship, the only qualification you'll need is a fully-validated frozen ATPL with MCC, and, of course, a class 1 medical. And preferably a few hundred hours in jets - but that's another story!
Scroggs