maybe "lamento" could be better translated with "i regret"? just a suggestion. like: I regret we had no opportunity/occasion to chat.
and I personally would prefer "students" instead of "pupils", but that might be my north-american influence.
"I'm sorry, that there was no chat.. Now, I have to go. Bye, pupils." Gelernantoj could also be translated to students. Babilejo means "place to chat", and are often used for chatrooms on Internet.