Good news from here. I drove to a motorway service station because I wanted to be absolutely sure I had no CCS charging issues before driving to the south coast in about ten days. Straight on to a Gridserve, no issues at all, first time of asking.
I then tried the Applegreen chargers across the way, and had a fair bit of trouble, but the trouble was the card readers that were being very temperamental. Other drivers were having similar trouble, but everyone managed to get on one way or another, and sometimes a charger that hadn't worked for one person would work for another. Once the damn thing had decided it was happy with the colour of my plastic it charged the car without any fuss. And despite all the faffing around and multiple card presentations, the only debit in my bank account is for the charge I actually got. No phantom "authorisation charges".