Joe, I believe BBC3 and BBC4 are broadcast as CBeebies and CCTV (or whatever is the kids' stuff) during the day, and they morph into grown-up broadcasting from 7pm. (Actually, there are many exceptionally good programmes on BBC4, so the Beeb can get it right when it so chooses).
Every year, GW is taken off air for Wimbledon. (As a fan, I enjoy the tennis - but even I find the saturation coverage a bit OTT). But Wimbledon fortnight doesn't explain the following two weeks' absence.
Four weeks takes us up to 20th July. The following week the Olympics start. So I presume we'll be granted ONE programme, thank you and goodbye for the rest of the summer, see you, if you're lucky, in the autumn. Bah, Humbug. I pay a licence fee too. I expect better - but shan't hold my breath - the triumph of hope over experience. 