Have you tried Captain Cooks, Spoils or Debenham's (their kitchen section is upstairs, and all these shops are upstairs) in Castle Court? Debenham's is expensive but they have a different range of gadgets than most shops (more posh, obviously); Spoils is more like plates and mugs but worth keeping in mind, and Captain Cook's has all sorts of stuff. Also, don't overlook the Pound Stretcher when you're in need of handy little things, they may be cheap but there are a good stop gap for some things.