Brilliant, Cheers

These are the two words I've noticed myself starting to use. Brits use "brilliant" like Americans use "awesome" or "great". For example: "You mean the account is created for me, and I don't have to? That's brilliant."

And "cheers" isn't just a drinking toast. Here it's also usually the last thing you say to someone. Like if I buy a magazine, where I'd normally say "bye" or "thanks" when I leave, now I'm saying "cheers". It's also how phone conversations are often ended: "cheers, bye". Though I haven't graduated to "cheers, mate" yet.