You'll find English on a lot of the street signs here, and its on just about everything in the Subway. That said, do yourself a favor and try learning some 한굴 (Hangul). Its their alphabet, and its all phonetical. I picked it up pretty easily myself. If you have a week or two, you should be able to get familiar with most of it, just spending a little bit of time each day. While you can get around alright without it, its made my experience here more enjoyable. It feels slightly less foreign here now and its fun being able to sound out what is written everywhere. There are also a lot of English loan words used, so its extra fun when you read a sign and figure out its actually mostly English, just written in Hangul. Knowing Hangul also saved me some time in one of the subway stations, I was trying to figure out which direction I needed to go, and the huge map on the wall where I was at only had things in Hangul. I could have found another map with English on it if I had to, but it was really nice to figure out where I needed to go using the map that was only in Korean.