I arrived in a hotel and the receptionist asked me if I would take the breakfast tomorrow in this hotel. He said "Will you take the breakfast" and told me that I could give my answer once I had made myself comfortable in my room. I answered "ok" and ten minutes later after making my self comfortable I answered "I will take it " Could I have answered "I'm taking the breakfast tomorrow at the hotel".
The present continuous tense can absolutely be used to talk about an action to be completed in the future! One of the applications of the present continuous tense is precisely this. Remember the other three tenses? (will + verb infinitive without "to"), (be + going to + verb infinitive without "to"), and the present simple tense. The present continuous tense can be used in cases where you have no doubt in your mind that you are going to do something. You have thought it out well and made plans for it. Unless there is an earthquake to reduce the hotel to rubbles, by golly, you will have breakfast tomorrow morning at the hotel! So, you could've said, "I just wanted to let you know that I am having breakfast here tomorrow morning!"