If anyone is going into Cambridge between now and May (I assume bank holiday) there is a temporary stand in the Lion Yard. It is under the escalator across from the HMV.
They have sodas (A&W, Grape, Mountain Dew, Vanilla Coke)
Pop Tarts, cereal, Aunt Jemima, peanut butter (natural and ummmm, not natural:-) jelly, other baking stuff (the guy said on the weekends they will have a bigger stand with more stuff like cake mixes) lots of candy nerds, Hershey, Charleston Chews, Runts, Gobstoppers, cookies nutterbutters and others. They had pretzel M&Ms.
And lots more. They have a website, but I can't remember the name possible due to sugar overload.