I think that mainly, employers are looking for whether you have a degree or not, and your final grade at the end of it. They might prefer a higher university over a lower ranked one, but only if the grades are the same for both applicants.
The main thing to consider is whether you'll enjoy Greenwich - a degree is still a degree, no matter where you go, at the end of the day. You're the one that will have to be living there for three years or so. You need to be sure that you're going to be happy to be there.