The US adapter is auto voltage sensing so can take either 110V or 220V so will work anywhere in the world even if it's not shipped with the UK plug. Instead of an adapter or converter, just pull off the actual plug part from the charger (thanks apple for making this 2 separate pieces) and you'll see that there's a normal figure-8 plug in there (see adapter type C7 on this page: IEC connector - Wikipedia, the free encyclopedia). Then just go buy one of those from a computer or general merchandise store and it'll work...