“it will take place” vs “it is taking place” (arranged actions in the future)

I've been trying to find an answer to a question that has been bugging me for quite some time now: If I have to express future in an action already planned and arranged can I use both I will + infinitive and the present continuous? If yes, is there any differences in the use of one form vs the other?

Examples:
1. I'm seeing the doctor at 5 pm vs I will see the doctor at 5 pm.
2. The meeting is taking place on the 5th of June vs The meeting will take place on the 5th of June.

I'm asking this because I was taught that in such instances you MUST use the present continuous while using the will+infinitive form is incorrect (even though I see many instances of the latter on the internet).

You have been taught an incorrect distinction.

All the constructions used for future events—will VERB^inf, BE going to VERB^inf, BE VERB^pr.ppl, will be VERB^pr.ppl, BE going to be VERB^pr.ppl, BE to VERB^inf and even VERB^fin—are practically equivalent.

There are no doubt statistical preferences in different situations: BE to VERB^inf tends to be used more often with situations involving some sort of obligation, will VERB^inf tends to be used more often with earnest promises, VERB^fin tends to be used with situations when the speaker is consulting a calendar or engagement book (and with translations of Richelieu’s instructions from The Three Musketeers!), and so forth.

But none of these tendencies rises to the level of a grammatical “rule”.