Future tenses

I’m sure, I’m afraid, probably, perhaps)
I believe he’ll have to cancel his trip
He’ll probably be late
For promises
I promise I won’t forget you
For on-the-spot decisions
I’m so tired, I’ll take a break
For threats
If you don’t study hard, you will fail your exam
For hopes, fears, offers, promises, warnings, predictions, requests, comments, etc. especially with : expect, hope, believe
I’m afraid she will be busy tomorrow
For things we are not yet sure about or we haven't decided to do yet
Maybe I’ll go to the cinema later.
(Shall woth I and WE is typically used in interrogative form when makinf suggestions, offers and asking for advice)

started future time
This time next week I’ll be sunbathing in Barbados
For actions which will definitely happen in the future as a result of routine of arrangement
She will be driving to Milan tonight
When we ask politely about someone’s plans for the near future
Will you be watching the show tonight?

future action
She will have written for essay by 7 o’clock

to go shopping tomorrow (she’s planning to…)
BUT
We use will fot on-the-spot decisions
I’m thirsty . I think I’ll have a glass of water
To make predictions based on what we see or know
There are black clouds in the sky. It looks like it is going to rain.
BUT
We use will to make predictions based on what we think of imagine
I think she’ll become a great writer.
To talk about things we are sure about or we have already decided to do in the near future
They are going to build a bridge here ( It has been decided)