Quote Originally Posted by Valda View Post
Мне придётся говорить с ней

How do I say it in future tense?
Valda, it's already in future tense. Придётся - perfective, future tense.
If you need to show some nuances, you should play with the second verb (using perfective or imperfective form).

Мне придётся говорить с ней (the second verb is imperfective)
Мне придется поговорить с ней (the second verb is perfective)

What's the difference? The first one implies that you suppose it will be a long or/and detailed conversation, or possibly even a few conversations. The second one just implies one conversation in the future.
What form do you have to choose? Actually, almost for all your situations perfective form is preferable. Except for the situations where you should make an emphasis on a long-time action.