OK, managed to get the lights rigged up inside the house as well today. As it turned out the straightening pieces of MDF I had to fix earlier to the insides of the walls to correct the warping, turned out to be the perfect place to attach the internal lighting circuit too, simply hot-glued into position...
I hope this upload works... here's a quick video of the twinkling light effect...
So next on with the roof tiles, then painting...