Well, all done and dusted bar the cheapo recharge.
I vastly over-estimated the distance to the boarding cattery - it's exactly a mile. When I went out to the car its 11-mile range estimate had dropped to nine miles. Still 5% charge showing. I allowed it to go into power-saving mode when it asked, this time.
The mile to the cattery is a 20 mph limit for half the distance, and since there was nobody behind me I just rolled on at about 20-30 mph for the remaining half-mile. Picked up the cat and headed back. Again there was nobody behind me so I just rolled back down the hill at 20-30 mph again. Then I saw someone standing leaning on the lamp post by the 20 mph speed limit sign, which looked a bit odd. As I passed I saw it was a cop with a speed gun. Obviously he wasn't in the slightest degree interested in me. But the bit of road he was actually pointing the gun at is a 60 mph limit. Anyone doing over 60 there is certifiably mad. The issue isn't people speeding in the 60 mph section, it's them not slowing down for the 20 mph limit, and he wasn't going to nail them doing that from where he was standing. Very peculiar.
I was so confident I even detoured into the village shop for the single item I'd inevitably forgotten when I cycled up for some supplies this morning. Total mileage for the trip, 2.4 miles. The car was still showing 5% and 9 miles range when I got home, just as it had been when I left. Also, 5.3 miles/kwh from start.
All I need now is a continuous charge schedule to 100% from Octopus tonight, and my long charge will be done also. I may play with the "ready by" time till I get it.