Futures	

be going to

I'm going to stay in tomorrow 	be going to

It's going to rain	will

I'll call you later	will

I doubt it'll rain	
present continuous

I'm having dinner with my sister tonight	present simple

The plane leaves at nine	future perfect

I'll have finished by ten.	future continuous

We'll be having dinner at eight.	
intention / personal plan	strong prediction (present evidence)	prediction (simple)	spontaneous decision, offer etc	
arrangement or appointment	timetabled (scheduled) future	already complete on or before a date in the future	already in progress but not completed at a specific time in the future	
I'll tell Tim you called	I'm sure I'll pass the exam	I'm going to buy some new shoes	You're going to slip on that floor if you're not careful	
His course finishes in June.	What are you doing on Friday night?	I'll have retired by the time I'm forty	Don't come before five - we'll still be painting	

Answers	

will

I doubt it'll rain	prediction (simple)	I'm sure I'll pass the exam	
will

I'll call you later	spontaneous decision, offer etc	I'll tell Tim you called	
be going to

I'm going to stay in tomorrow 	intention / personal plan	I'm going to buy some new shoes	
be going to

It's going to rain	strong prediction (present evidence)	You're going to slip on that floor if you're not careful	
present continuous

I'm having dinner with my sister tonight	arrangement or appointment	What are you doing on Friday night?	
present simple

The plane leaves at nine	timetabled (scheduled) future	His course finishes in June.	
future perfect

I'll have finished by ten.	already complete on or before a date in the future	I'll have retired by the time I'm forty	
future continuous

We'll be having dinner at eight.	already in progress but not completed at a specific time in the future	Don't come before five - we'll still be painting