I studied Meteorology as a mature student as the University of Reading. To do this I took A-Level Maths using a distance learning course fro the National Extension College. It really wasn't that expensive, and I could work at my own pace while still employed. The downside is you have to arrange to sit to your own exams, which I did via a local school.
Physics was more troublesome, as most qualifications require lab work. I was lucky in that I was accepted on a Science Foundation Degree which brought me up to speed in the maths and physics required for meteorology. Sadly the course is no longer run at Reading, but I believe Leeds still has one with progression into meteorology.