要去 doesn't mean "going" all the time. It can mean "want to go" Compare the following sentences:
我要去机场 (I want to go to the airport)
我(快)要去机场了 (I am going to the airport (soon))
In the first sentence, the 要 means "want"
In the second sentence, it's the 要 and 了that makes 要去...了 mean "going"
The same principles would apply for 做:
我要做完功课 (I want to finish my homework)
我(快)要做完功课了 (I am finishing my homework (soon))
Hope this helps! :)