Korea is considered an "English Crazy" country. They spend unbelievable amounts of money having their children learn English in private hagwons, or specialty schools, their tee shirts have nonsensical English written all over them, and foreigners get shouts of 'HELLO!" from passing school children. You see English everywhere, but the amount of English actually spoken in Korea is very little. It is necessary to pick up enough Korean to get by, but usually this only take a few weeks of learning useful phrases and applying them to your day to day life.
Luckily, "Konglish" is widely used and many words are the same in English and Korean. If you speak very slowly and use actions, you will almost always be understood - don't worry!
If you wish to learn Korean in a formal setting, there are several ways to do it:
First, you can take a course offered by the government. These typically take place in community centres and are free of charge. Usually, though, the entire lesson is in Korean and your classmates have already studied before coming so they will probably be ahead of you (even if it's a beginner class). These classes usually attract people from developing countries who immigrate to Korea to work. You can find community centres all over Seoul. Try the Galwol Community Welfare Centre (http://kongbubang.wordpress.com/), the Ha…