Is the Seoul dialect the only one I should focus on?

I'm planning my first trip to South Korea next year and I'm nervous because my listening practice has been entirely based on standard Seoul-based content. I'm worried that if I travel outside the capital or encounter older speakers, I won't understand a thing. Should I try to learn regional variants now, or is it better to just master the standard Korean honorifics first to ensure I’m being polite wherever I go?