I'm not sure if there's a specific rule for this, but I'm sure it'd come under dangerous driving - I was cycling home last night and a woman driving towards me on a very busy road was applying eyelash makeup in the flip down mirror with solid on coming traffic!
Last week, in a similar place, I was nearly wiped out in the cycle lane by a chap drifting across in preparation for a lefthand turn 100m down the road. He got close enough that I could see the phone he was playing with on the passenger seat beside him.
I wonder what tonight will bring!