BRITISH PHRASES
Au fait - Another one of those French expressions that have slipped into the English language. This one means to be familiar with something. I'd say at the end of reading all this you'd be au fait with the differences between American and English!
Baccy - Tobacco. The sort you use to roll your own.
Bang - Nothing to do with your hair - this is a rather unattractive way of describing having sex. Always gets a smile from Brits in American hair dressers when they are asked about their bangs.
Barmy - If someone tells you that you're barmy they mean you have gone mad or crazy. For example you'd have to be barmy to visit England without trying black pudding!
Beastly - You would call something or somebody beastly if they were really nasty or unpleasant. Most people would consider you a snob or an upper class git if you used this word. People like Fergie can get away with it though.