From a non educational "experienced Mac users point of view", Apple's been taking more and more in-house over the past 5 years. There aren't many 3rd party vendors left on the high street and I suspect that also applies to tech support as well. A contact deals direct with schools and works for Apple UK, so I suspect from that alone, they don't farm much out to third parties nowadays. As for in-house support, I'm aware that Cambs Uni maintains it's hardware in-house.