Just a brief update:
I'm in a bit of a holding pattern, still waiting on my basic kit to arrive. According to UPS it is due in my hands tomorrow. I've also been trying to finish some of my other (real-life) tasks so that when the package does get here I can devote time to getting familiar with it.
Up to now I've just been experimenting with my older Model B Raspberry Pi and playing with OpenHAB. Also some reading up of EnOcean to explore the possibilities of re-programming some of the sensors.
My conclusions so far are that OpenHAB is very powerful, but can be fiddly to configure. Documentation is poor in some areas.