The Mezzanine

I'm basically with Speaker. Though 'elevenses' is a tad Winnie the Pooh for me.

'Tea break' is the all purpose one I would use for everyday needs - morning and afternoon. It's distinguished from afternoon tea by a) being about a break in work rather than actually specifying any particular meal and b) tending not to come with scones and cucumber sandwiches; oh and c) actually, it doesn't need to involve tea either, whereas afternoon tea certainly does. I never normally say 'afternoon tea', unless I mean some huge production involving doilies and aunts.