Reported last week that lifton is doubling to 16. Not sure where they will put them. 16 would make about 30% of the total spaces in the carpark supercharger bays!Exeter looks to be turning into a pretty big hub now (they need queue management..) - aside from that Tesla has decent coverage up the M4 and M3/A303 (less so here). Not sure about up the M5. M40 Banbury is there for everyone too.
So realyl that leaves the leg of Cornwall. Tesla has Lifton and cambourne so you have a handy 'last mile' stop you can use for local travel if you're heading deep. So for non-tesla 'all' they really need is a couple of equivalents to those two deeper into cornwall.. hopefully soon?
Wiki - UK and Ireland Supercharger Site News
Maidstone I've stopped there a few times coming back from Chunnel, but I don't do that anymore as everyone coming off the Chunnel (ferry too I expect) stops there and limited (6) stalls, old 150kW charger (so charging speed is as per "paired" if other stalls are full, even if not also had to...
teslamotorsclub.com