I am having lunch
I have lunch
I have "a" lunch ? What am I, a food distributor ?
"What are you doing tomorrow?"
"I have a lunch"
"Yes, my Italian conversation group is having a lunch"
the translation cannot be "I have a lunch" is has to be "I have lunch", "I have a lunch" is just vernacular
I think you should accept luncheon here as well as lunch
no. lunch is an everyday meal; luncheon is not