Hi Tanya.. I had been wondering the same question like you have but I have found a good material to learn from. Here it is said that to talk about future we could use Present Simple, Present Simple Continuous, Future Simple and Be Going to. 1. Present Simple. We use this tense to talk about events that have been timetabled. E.g. The meeting starts tomorrow. 2. Present Continuous Tense (with a future time expression). To talk about an arrangement, and the near future and we need to say WHO we are doing something with, WHERE and WHEN. E.g. I'm meeting Tsania tomorrow. I've phoned her (example of arrangement). I'm watching basketball match with Judy this evening.(example of near future). 3. Simple Future: is used to make spontaneous decision, offers, promises and predictions. 4. Be going to : is used to make prediction (based on the present evidence) and plans that we have decided to do.

will --- неопределённое be going to --- намерение Present Simple --- после слов when, after, if etc