I work IT in schools, state and private, primary and secondary. I was one of first-batchers for the original RPi.
Few resources are actually advertised and available to teachers. The only educational-focused content offered is some random tutorials on websites, or third-party stuff from people that have nothing to do with the RPi. Most RPi's are bought, used a couple of times, then sit in a cupboard. Like a lot of other cool technology, I'd like to point out, but there it is.
The BETT exhibition is the UK's educational IT expo. For a few years it was "all about the RPi". People selling the units. Few resources. No teaching resources for those places that need it most (chances are that if the kids need teaching how to code, so do the teaching staff!), no training, nothing. I haven't see the foundation at the BETT ever (despite being run by a UK guy who claims the purpose is education?).
This year it was "all about"... well, not much. Some of those BBC Bit things were on a display board but you couldn't buy them. And, same thing, no resources or information about how to teach with them or the educational value.
I work in a prep school at the moment. We were beta-testers for the .NET Gadgeteer kit. We have kids working at secondary-school levels and beyond. We build and fly home-built drones with the boarding kids. We STOP teaching crap like Scratch in Year 3 but we go up to Year 8.
The RPis I found in a drawer when I started there. I wasn't surprised, as mine was in the attic by then too. We never bought the Model B's. We won't be touching the BBC things either.
To be honest, it's easier just to let the kids (rich kids!) buy their own gadgets and then integrate them into the lesson. All the kids have iPads (not my choice, but I have to make the best I can of them), if they program they do it on those or on the PC's in the school. The geeks turn up every Friday evening for "the geek club" where we do things like C programming, machine code, building drones and kitting up Arduino kits.
I've yet to see what the actual educational value is in the Pi - I'm sure a REALLY good teacher can use them, as ours did, but that's to do with the teacher, not the device. They do just as good a lesson with pen-and-paper, an iPad, a lego-kit, or some $5 Arduinos and a soldering iron.
And with almost zero teaching resources sold with them, most teachers who aren't up to speed (which is sold as being half the point of pushing IT in schools, that the teachers are behind the pupils themselves) won't touch them as they see them as "just a gadget" with no educational value or help in their teaching.
15 years in IT in schools, story has been the same in all the schools I work in. It used to be QX3 microscopes, then visualisers, then Raspberry Pi's (and Scratch at the same time), next week it'll be something else.
You just missed this year's BETT. The only RPi's I saw were running Lego kits and things that ANY device could be running. And nobody was really selling the RPi or associated resources... I think I saw one stall selling RPi cases that were twice the price of the same thing on Amazon.