Take a look at Geographical_renaming#Naming_disputes; every article listed there is about a naming dispute, and separate from the article about the entity whose name is in dispute.  With one exception: British Isles.  Take a look at Derry.  A good article about the city; the first section after the intro is about the naming dispute (already entioned in the intro) with a link to the separate article about the dispute.  The rest of the article takes the name "Derry" which is the title of the article and uses that in discussing all other aspects of the city.  I think that is a good model for British Isles.  Let us take "British Isles" to mean "Great Britain, Ireland and the rest"; mention that (1) many people dislike "British Isles" and use some other words to mean "Great Britain, Ireland and the rest" and (2) some people use "British Isles" to mean something else; link to another article discussing these issues; then move on and discuss the other aspects of the isles.   What other aspects? A few examples: Geology of the British Isles and Trees of Britain and Ireland; Climate of the United Kingdom could be expanded into Climate of the British Isles since Ireland#Climate is pretty sparse; likewise British avifauna as against Ireland#Fauna.  I don't think nationalist sensibilities can be offended by observing that the climate, plants and animals in Britain and Ireland are similar; a single article to cover both is better than nothing for Ireland (it can be refactored later when an Irish expert becomes available).  How much of Category:British Isles needs to be summarised in the head article is just a detail.