Only one person has said this so far so it bears repeating..
Uni isnt like school - Seriously, its not! If you dont enjoy your subject, its very unlikely you'll put the work in to do well in it. So choose something you enjoy, and worry about jobs after you've done it.
I started my degree in pure physics, but switched to natural science after a year to get a little more perspective. (I've ended up specialising in two areas, Astrophysics and the Philosophy of Science - who'd have thought!) This is coming from someone who wanted to study Physics at uni since I was about 14.. at least I thought I did. I cant imagine making it past the first year in a subject you didnt enjoy at all.
If you want to talk about money, though..
Dont do economics. Unless Durham's opinion is different to the rest of the world, if you want to get into banking, investments etc then the best degrees are either pure science or maths. Economics just looks like a joke course in comparison. Everyone I've spoken to at uni (staff as well as students) about this over the years have said the same things.
If you want to do science, I can recommend a Natural Science course. It lets you pick an interesting range of modules and keeps your options open. However, there aren't many places that do them (maybe 10 - the ucas site would tell you easily enough) and they generally have higher entry requirements than normal courses. (For example, in Durham the requirement for Physics is AAB, for NatSci it's AAA as theres more demand.)
Hope that helps a little