Train travel is available with Korail or the KTX bullet train direct from Seoul to Gwangju. The trip takes around 3 hours at a cost of about 39,000 Won, though you should note that the trains leave the Seoul Yongsan station and not the Seoul Main rail station.
You will be amazed at the Gwangju bus terminal where buses arrive and depart for other Korean cities since it looks more like an airport building than a bus station. It is commonly referred to as the ‘Busuh-Teo-mee-nal’ by the local taxi drivers who know the place well.
There are very few problems associated with getting around Gwangju. The Subway is cheap and you only have to pay 1,200 Won to any destination and the bus service is popular but you will need to understand the meaning of the different bus colors. The Red buses are the Express buses.
Taxis are inexpensive, charging only 2,800 Won for the first 2 kilometers and 100 Won per Km after that, in fact depending on the traffic you can cross the whole of the city for about 10,000 Won.