Differences between will, going to and doing+V to describe future time in everyday English

Question

I know there are some subtle academic differences between them but do native speakers really consider it before choosing the correct tense to use or they are interchangeable in everyday English?

Answer 1

I don't think native speakers consider which one to use, it's just that different ones come naturally in different situations.

(In British English) "If you eat too much cake you will be sick" is a prediction. "I'm going to be sick!" is an urgent warning. However, I'm going to can also be a prediction - "I'm going to miss you when you leave." If you are promising to do something, it's "I will give him your message."

"I'm taking my driving test next week" implies an arrangement that is already fixed. I think if going to was used, it would imply a less definite date. "I'm going to take my test this summer if I can get enough practice."