Just saw this. For the record, Muppet Wiki does *not* say it stopped with "Honk of Honks." Rather, a user added a list of episodes where airdates are confirmed, and a note above that season states the list is incomplete. So yes, it did make it to the very end. As to what happened, even home video releases in the UK have been scattered so the final episodes (and just about any with the Captain's replacements) aren't in wide circulation, unless someone over there has the episodes taped from broadcast. But from assorted interviews, the final episode was pretty close to the US version, at least as far as the Fraggles meeting (speculation, but if the human character at the time was moving, they probably tied it to something like a job or simply a vague "we're moving away" rather than tying it to someone's illness, unless it was a random relative). Additional Fraggle puppets were sent over for when they filmed the finale.
It's unlikely at this point, but if HIT ever decides to release a separate fourth season, that final UK episode would be a nice extra (and yes, it was the only co-production to go all the way to the end and reach a definite conclusion).
It's unlikely at this point, but if HIT ever decides to release a separate fourth season, that final UK episode would be a nice extra (and yes, it was the only co-production to go all the way to the end and reach a definite conclusion).