The C-Map site has a sort of configurator that will tell you whether you can use NT or NT+.
Beware if you are trying to use new NT+ cards, there are some size limitations which prevent at least the 'Wide' cards working. I've tried to get a sensible response from Raymarine, Jeppeson etc as to whether local cards work - to no avail. RM say ask Jeppeson, and Jeppeson say ask Raymarine. Don't know about the NT cards.