Get a Virgin prepaid sim for 10 quid in London at any cell phone joint (or even at Heathrow or Gatwick) and you'll be set - great local/national/int. rates (even to the US.) And it' easily rechargable. But DON'T use it in Germany!! Crazy high roaming rates. For Germany, I haven't found nearly as good a deal for a prepaid SIM - usually the min. to buy is about 30 euro. You may be better off roaming on Cingular there unless you are making a whole lot of local (in Germany) calls.