Historically Tesla stick a variety of pins in the map which are not much more than that. It makes sense to have something NorthWales/Cheshire and Chester area would be logical - far enough from the Manchester service centre but not so far west that the owners thin out. But whether its Chester, or Crewe or Wrexham and whether its this year or next or the year after, who knows.
There has been a supercharger coming soon near Crawley for 5 years to my knowledge as an example. I know superchargers aren't service centres but it seems to be the way they work. People on the owners facebook group run spreadsheets of planning applications when they find them etc which may or may not help, but either way, I wouldn't personally hold my breath not that you need a service centre very often with rangers covering a lot of the work.