After much playing about with the colourduinos ive decided to go for the neopixel 8x8 matrices, they are more expensive and have a less desirable pixel layout (not square and further apart) but a hell of a lot easier to actually do something useful with.

after a bit of coding, the rest was a breeze, arduino nano stuck on the back of the displays, RTC hooked up and an LDR too, basic code tying the LDR value to the global brightness control in FastLED library. Boom! Done!