Best Understanding of the Issue
Glad you got it working a bit better. But like I said, I don't actually support UK products, so I'm overstepping my boundaries a bit. I'd really encourage you to call up or chat with you country's support: http://www.samsung.com/uk/support/model/UE46D8000YUXXU
But here's my best shot.
As far as the relationship between ARC and AnyNet, AnyNet is Samsung's special flavor of CEC-HDMI. By special flavor, I mean that AnyNet is meant to work with other Samsung products, and that's all. When it works with other products besides Samsung products, it's a happy accident.
But to do what you want to do with the audio, I suggest you get a specialized remote to be able to handle multiple devices.
Hope that helps!
-- HD Tech