When I moved to the US on a student visa 2.5 years ago, I travelled with just my free luggage allowance... two suitcases, 50lbs each. I was going to be living in the US for between 4 and 6 years (PhD student) which meant I had to pack up my entire life into 2 suitcases (well, actually it was more like 1.5 suitcases, because half of the second case was filled with English food to take with me
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It turned out okay though, because I had all the essential things I needed with me (favourite clothes, music, DVDs, books) and anything else I wanted, I just bought when I got to the states. I left the rest of my belongings at my parents' house, which was actually a good thing, because I ended up moving back to the UK after 8 months (although, by that time I had about 3 times the amount of stuff I started with - I ended up with 3 suitcases worth of stuff, plus I shipped 4 boxes home too)
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How long are you going to be living in the UK for? If it's just a year, I would bring as little as you can, because you're going to have to get it all back to the US again at the end of the year.
A few years before I was a PhD student in the US, I did a study abroad year there too. I took, I think, two suitcases with me for the entire year, and still had to ship two boxes of stuff back to the UK, plus get my friend to take back several things for me when she visited home for Christmas!