the Instructor #2 who had sent me on the XCQ was very surprised to learn that I had never been on a fly-away before and so had never done a solo landing at another airfield
It is actually very common for QXC students to have flown to one airfield but not the other on their QXC. So I am surprised the Instructer was surprised!
For most people their first solo land-away is at the second airfield on the QXC. I'm sure the QXC is deliberately setup this way. It is a test to ensure that you can find the airfield without having an instructor on board. The fact you flew past the airfield is a proof that the test is a valid one! (BTW: I got lost coming back from my second airfield on my QXC - only the excellent visibility allowed me to locate myself again!). So don't get too hung up on the fact that you had not landed at a strange airfield on your own before the QCX; very few people do.
It does appear you have been subject to some very lack instructing. As well as the lack of communication between instructors already commented on by other, it is a significant failure that you have not been trained to use the Radio Navigation Equipment in the aircraft, and not to have been give guidance on how to obtain (and use) a QDM, prior to your QXC.
It is difficult for any school to standardise the approach taken by any two instructors, as teaching styles are bound to vary. But the school should be making an attempt at standardisation - it doesn't sound like your school is. This has to be a bad thing for student progress.
As Whirley says, it sounds like you are doing fine inspite of this school.
At least you will know what to say is someone asks you if you can recommend a flying school...