Well, my brother is something of a genius and is going to read philosophy and maths at Bristol University. If you want philosophy to aid in the production of anything even resembling objective knowledge, then mathematics is essential and is applied through logic, and such.
I had never studied it extensively, but I do an immense amount of reading of philosophy outside my studies. Any essay you ever write on anything will be enriched with a good knowledge of philosophy, as will your life in general. I have studied a couple of political philosophy modules within my degree, and not only do they offer some of the most enjoyable study opportunities, they are genuinely useful within my useless degree.
I'd say go for it, I suspect you will enjoy it immensely.
EDIT: Perhaps I should say that I don't think that dedicating oneself to the study of philosophy is as valuable as doing so with a natural science. Especially how much more advanced our natural science is becoming, and how much more we are learning through its method. And that isn't just because my younger brother is going to do a degree I would have loved to do, at one of our finest universities... -.-