How does this limitation apply?
It applies to a G registered aircraft wherever it may be. Non G reg aircraft operating in the UK are subject to Art 223.
Is it any different from saying on a forum, "I'm off to x destination - anyone want to come along for the ride?
Yes, it is not wholly within the premises of a flying club therefore; if you carry passengers, invited this way, you cannot cost share with them under the exception granted in Art 267!