Test question.

Hola Korbel

I believe the sentence you are referring to is linked to a different lesson, [competency id= "6003"]

In this lesson we are explaining that we use verb IR in El imperfecto (iba, ibas, iba...) followed by "a" + infinitive when we are expressing what we have/had already planned in the past (and in this specific case in your sentence, is still the plan going ahead). So you need:

"¿Vienes a la fiesta?  No puedo. Iba a ver el partido en la tele."

This implies that I had already planned to watch the match. (so I am not going to the party, I am sticking to my plan)

However the English translation in the present continuous can be misleading, so we will change it to "I already planned to watch the match."

With reference to your other query about using iré a ver VERSUS voy a ver, as a general rule, we tend to use "voy a..." when it is about something that you've planned and there is no doubt about it, so you are going ahead with it. However if we use "iré a...", that brings a bit of uncertainty to the plan. So we may have thought about it but the plan may change. Also, the simple future "iré a" is generally used to express something happening in a more far away future. 

Having said that, the difference is very subtle, though.

I hope this helps.

Un saludo

Inma