You don't need a high Charisma. If you have SH she can boost your skill checks with spells. Buuuuuuut more importantly it will probably be more fun and entertaining for you to watch your barbarian stumble through conversations and resort to other methods to get things done.
One of my favorite parts of Fallout 2 was that you got special interactions that happen when you were low int or cha.
I say, play into the stereotype and enjoy the ride.
Important note: Use your MC to handle the conversations. Your relationships with companions are built on their reactions to the things you say and do. If you let a companion lead the conversations, you'll lose out on a lot of content.
