England is only a part of the UK so that's even more accurate of an answer than country.
England itself is a country.
I go by NGO's like the UN and what have you and in alot of organizations it's "United Kingdom of Great Britain and Northern Ireland" not the parts of the UK listed separately.
England doesn't negotiate and make trade and defense deals on its own separate from Wales, Scotland and North Ireland...at least for now that may change soon once certain things are finalized and the shit hits the fan.
Have fun with Brexit!