No controller should be caught by surprise by an aircraft going around, although in good weather they're not common, every sequence has been arranged with the possibility of a GA in mind.
Any well trained ATC should know not to talk to crews during high workload situations such as takeoff, landing, and go around / missed approach unless its an emergency situation. It is a requirement here that pilots advise going around (although its certainly not a priority) and my response to that is "roger, when ready report intentions". If its really that serious, he has already called "MAYDAY!"
Here controllers are required to complete 10 hours of flight deck time prior to being issued with an ATC licence, is this not an ICAO requirement?