1. It was nice chatting with you. 2. Well, it's getting late. 3. Anyway, I should get going. 4. (formal) Sorry, but I'm afraid I need to... 5. I'm sorry to cut you off, but I actually gotta run. (cut you off = interrupt you)
This experimental UK based school that was found back in the rebellious sixties definitely deserves a mention since it was one of the most progressive schools worldwide, especially if one takes into account how strict British life was back then. This school allowed its students to do pretty much whatever they wanted. Fancy a cigarette during class? No problem. Plow through the school grounds on a motorbike? Ditto.