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 queue), and nothing to do in the vicinity. So I choose to charge before boarding Chunnel on return, even if I miss a train, rather than get stuck waiting / slow-charging at Maidstone.
On return leg any delay just adds to arrival time, but on outbound leg, if you want to make a particular crossing, then a delay is less acceptable
If you are in a bind (outbound) then there is a Supercharger in Coquelles, Calais (i.e. outside the Chunnel complex). If you are heading SW along the cost, from Calais port, it will be on your way ... and if you are heading SE it won't be and the next one, SE, is Lille which is be another 70 miles