@Kev the solution is a RPi with the Adafruit 2.8in TFT screen. A custom web interface forced on to the user obviously compiled specifically for me. The bonus of this is power usage is low and once i have a working image I can clone it and if it ever crashes just replace the SD card and reboot. I will look on eBay but little will change my mind now I fear. Good heads up though 
And I have already test driven that hack myself, not impressed with it and it doesn't completely fit my needs. I did find a similar product just for lights with dimmer option too but again it's the insecure protocol that doesn't sit right with me. I know it's only lights but with my job I be loath to have a security weakness in my home system
I have seen articles on how to create your own secure wireless interface with a PI, after that it would just be a case of fitting the relays to the receiver to control the curcuits. The issue with that is that I will have issues getting it past a Part P inspection. Hence z or lightwave (and the additional cost) 
@Mark - I had no idea. Glad I asked....right off to look at mains powered amps 
OK on that. You still have to package up the Pi+screen to look nice, though.

That'd be my downfall with that solution, I think.
I have put a RFM12B module on my central node, so I can code up support for pretty much any RF protocol given the spec. and control it very flexibly. I already have some temperature measurement nodes built. I have it in mind to make some more secure mains switching devices, but the craplin ones will do for now, and the worst that will happen is that a couple of pence appear on or disappear from the leccy bill.
I don't really feel the need to control wall light switches so don't need it to be part of the permanent installation (not that part P would bother me overly, TBH).
The problem with all off-the-shelf HA stuff is that nothing integrates with anything else, and nothing does everything well, IMHO. It's about time some open standards got established and supported.
You might also want to have a look at active speakers. They often go into standby in the absence of audio input, so the switching issue is solved, and they might make a neat solution with no extra "boxes". Some are probably cheaper than you could make them yourself, TBH, and they go all the way up to studio monitor stuff that would certainly be quite acceptable in a "main" Hi-Fi system IMHO (albeit at a cost).