今日外出の予定がありますかって英語でなんて言うの？

1. Well, if you ask your co-worker about staying inside the office, his answer will inform you about this query.
   "No, I think I'll take a walk around the park at lunchtime."
2. Similarly with this question, if the idea is or is not appealing, the reply should tell you what this individual's plans are:
   "Does outside seem appealing to you today?"
   "Not at all. It's raining. I'm not moving from this office!"

Are you planning to...? This phrase suits any situation when you want to know if the other person, has considered a course of action in a definite manner...
Planning= forethought.
"Are you planning to leave the office, at any point during the day?"

"Do you have any plans outside the office today?" asks a person if they have anywhere they need to go or plan to go that is outside of the office that day.

>Hey, are you leaving the office today?

>Do you have any external meetings today?

>Any plans to leave the office today?
*external meetings= outside your office. Meetings at other peoples offices.

All the above sentences are good to use and are clearly asking if he/she is planning to leave the office.

In the first sentence, you have used the preposition 'over' which in this context means 'from the beginning to the end of (a particular period)', in this case, it is the lunch hour period.

In the second sentence, you have used the phrase 'venture out' which in this context means 'to go out of something cautiously', in this case, the office. You have also used the preposition 'during' which in this context means 'from the beginning to the end of (a particular period)', in this case, lunch hour.