My lighting unit is now complete In the end I used 60 LED units, 20 RGB, 20 Cool White, and 20 Warm White. These are connected to a TC420 LED controller, and a power adaptor from eBay. The software to set the light program is PLed, and after a bit of fiddling becomes pretty easy to use. Here is the light unit during construction. The LEDs are supposed to be self adhesive. But, as with everything that is supposed to be self adhesive, some of them fell off after a day, so I ended up screwing them in place.
This was the first test of the lights with all channels on full power:
And a video of how they look now, with my sunrise and sunset programmed in. And a little moonrise too!