On the way home, we called at Exeter Services - the chargers were busy, but there were plenty of spaces. We had about 30% in the battery, and ZapMap was suggesting we stopped at Leigh Delamare to top up. But having experienced out-of-use chargers on the way down, I thought it best to charge when I could, rather than when I had to. The charger started and stopped twice (and charged me 19p!) before starting properly. I got about 65K out of the charger, so we sat in the Services' lounge for 20 minutes, and left with a full-ish (90%) tank (the last 10% dropped to about 20k) which got me back home with some to spare (about 130 miles, Motorway all the way)
The only drawback with Exeter's otherwise excellent set-up is that all the exiting traffic is directed past the chargers, which makes reversing into the bays rather interesting...
After Exeter. the projected range started to drop dramatically (with me driving at 65-70

), so we went into Membury, which had a grand total of 2 chargers! Of course, they were both occupied with a queue waiting – we decided to move on to Chievely, which I hate, but it has a lot of chargers. But we then hit roadworks, and then a horrible accident on the other carriageway, causing everyone to slow down, and suddenly the range shot up again. Forcing my right foot to lighten up, I stuck to 60mph and made it home with about 15% left in the tank.
Lots of lessons learned this week!