I can't find anything yet from the caa about go pros, but looking at electronic flight bags (bear with me), I'm getting the feeling that any item not accessible during flight by the crew needs to be installed as certified equipment covered by the type certificate, but if mounted device is secured either on the flight crew (for example, a kneeboard) or in/to an existing aircraft part (for example, utilising suction cups), with the intention to hold charts or to hold acceptable light mass portable devices it doesn't...
Light mass portable devices attached by suction cups could be read across as GoPro?