Just spoke to my brother, who's been in the British Army since, oh, about 1983. No, Brits do not win scholarships to Sandhurst.
Some small foreign countries send their officer cadets to be trained at Sandhurst -- Jamaica, Fiji, and so on -- for which their governments pay the British Army. But Ireland is not one of those countries. The Irish military has its own officer-training facilities.
So yup, it looks like Ben's full of crap. But then again, we already knew that!