Meghan and Guy are very close, and yes he's a settled, older dog. But he definitely had to make adjustments with this type of relocation. Since he's been in London for awhile, Meghan has been traveling back and forth, so there would have had to be someone helping.
That said, there's no way we can know for certain exactly what Guy's current arrangements are, whether at Nott Cott, or with friends. Also, Guy is used to seeing many of Meghan's friends (including Lindsay Roth, Jessica Mulroney, Markus Anderson, et al.), as well as Meghan's neighbors, whose dogs he and Bogart often visited. The neighbor probably helped out on occasion when Meghan was traveling. When Meghan was dating Corey, he helped take care of both dogs and he had bonded with them apparently. He posted pictures of the dogs on his Instagram, which are still up. Therefore, it seems to me that Guy is used to being around different people. It's more a matter of his adjusting to a new environment and routine, than to new people. We don't know the set-up at the moment. I only mentioned the possibility that friends were helping out with Guy in London, because Meghan said, 'he's in the U.K.,' rather than 'he's with us here at KP.' It's not a big deal right now, one way or the other.