This thread brings back memories... almost 40 years ago I was in a similar situation to you, planning a year of study in England and wondering what to take in the way of a camera. I took a Nikon F and a 50/1.4 lens, and shot for the year w/ just that set-up. Great camera, but for backpacking excursions I wished for something smaller and lighter.
If it were me making this trip, I would follow Raid's advice above, except that my light backup camera would be an E-PL1, so a fast normal lens could also serve as a short tele w/ a micro 4/3ds adapter. A Leica, a 50, a 28 or 25, and the Oly Pen w/ the Pany 20 is a kit I'm looking forward to using on some overseas travels next summer.
But it's the OP making the trip, so I have to agree, given what he states about preferences, budget, and constraints, that Traveler 101 and fdigital have some very good recommendations. The E-PL1, btw, is about the same size as a Canonet G17 QIII or a Leica CL w/ the Pany 20/1.7 lens attached (ditto w/ the Oly 17/2.8). The E-P1/E-P2 bodies are slightly wider, but still quite compact, and having interchangeable lens capability gives you a lot of versitility.
Have a wonderful time, take lots of photos, and post some of them here!