For future plans you intend to do, use "going to": is/are/am going to VERB
I can't meet you tomorrow. I'm going to see my grandmother, who's in the hospital.
I'm going to end it with Alexis. I can't go on another day.
Is this relationship going to last? We both need to ask ourselves this.
I'm going to tell her what I think of her.
I'm going to get a new job.

Negative form: is/are/am not going to VERB
I'm not going to hurt you. Just put down the gun, and let's talk.
He's not going to make a mess. You are so paranoid.  OR   He isn't going to make a mess. You are so paranoid.

For future plans you have already arranged a time and place for, use the present continuous: is/are/am VERBing
John is taking time off in August, and we're heading up to our cottage in Vermont.
The nursing department is expanding into a new building this August.