Please, check my sentenses. Which is correct?

Linian_U Please, check my sentenses sentences. ...

I don't usually have a lunch at home, but ...

a) I am having now No.
b) I am having it now OK, but not the best choice.
c) I am having a lunch now

Linian_UI don't usually have lunch at home, but ...

And I prefer B, actually.

Thank you for your correction and answer

CalifJimd) I am having a lunch at home now Best.

Is it correct to say '... a lunch now? I thought we can't use 'a' with meals.

TS

No, it is not correct

It was my mistake.
Mister Micawber corrected my sentence.
I confused "lunch" with "snack"

We cannot say that 'have a lunch' is grammatically incorrect, but we can certainly say that 'have lunch' (and 'have breakfast/dinner/supper') is the native idiomatic collocation. As soon as we add modifiers (i.e. release them from their idiom), they become countable:

I had a wonderful lunch with my girlfriend yesterday.
They had a late dinner after the concert.
W

I took the modifier to be "at home".

A lunch at home is nicer than a lunch in a restaurant.

So "a lunch" appeared perfectly natural to me in the original sentences.

CJ