Peter, to my knowledge there is no where to go to find out why there are delays. Usually, it will be staff shortages, weather, or emergency traffic. This forum is probably the place to ask. As you've seen, on the day in question, it was staff. Something which is happening far too often in this country.
Not only is AsA struggling to get controllers through the door, it has failed to appropriately resource and prioritise its training. In my opinion the training is a game of 'come on, we dare you get through it' cleverly disguised as adult training. SoAsA may well have an excess of controllers (which I doubt) but they sure as goodness are not endorsed appropriately to actually work. The inefficiences of the organisation are astounding.