Is there an adjective meaning “from or pertaining to the British Isles” (or if you prefer “from Great Britain, Ireland or surrounding islands”, or “from the Atlantic Archipelago”, or whatever floats your boat)? I’m obviously not looking for British, but for a term that could be acceptable to an Irish person. I’m primarily looking for an adjective applicable to concepts relating to this geographical region, but if there’s a demonym, that would be interesting too.
In other words, if Webster’s is English beer, Tennent’s is Scottish beer, both are British beer, and Guinness is Irish beer, what adjective can apply to all three?
The name of the British and Irish Lions suggests that, in practice, the term you seek is “British and Irish”.