Switch courses at KCL?n

So I just got an offer from KCL for international development. But I also have an offer from Manchester for straight (BA) economics.

I have a feeling that there'll be more job opportunities with economics rather than with development and Im not sure which uni to firm because I wanna be in London for the opportunities but Manchester for econ.

I probably should've applied for econ at KCL, but I purposely applied for a niche course to get in with AAC predicted lol.

Is there any way to change courses if I chose KCL?