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England runs on 240V and 50 Hz, which basically means that most of your electronic devices from the US can't be used in the UK. Laptops are safe to use with a basic plug converter (different and cheaper than a voltage converter). For run-of-the-mill electronics, like alarm clocks or irons, your best bet is to buy them in the UK because they'll be heavy and difficult to pack and require voltage converters to use them in the UK.
Phone
CambridgeYou can choose to 1) bring your phone from home or 2) buy a phone in the UK. For your phone to work in the UK, it must have a SIM card slot and cannot be a CDMA network phone. Cell phone plans are much cheaper in the UK than in the US so you will be saving a bundle. See this page for Selecting a Cell Plan.
Paper + Notebooks
The UK uses A4 size stationary (not the 8.5"x11" "letter" size paper that is used in the US), so don't bother bringing any notebooks or paper with you from the US; you'll want to buy all your folders, binders, hole punchers, etc. in England. As for other random school supplies (e.g. tape, stapler, pens, etc.), you could bring them with you from the US, but they will take up valuable space and weight in your luggage and you can easily buy them in Cambridge.
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