Ban Dung is about 6000 miles from Wales. (5949 miles from Cardiff).
The easiest way to get there would be to first get to London Heathrow airport. Then take a flight to Bangkok. (11 hours 20 minutes with Royal Thair Airlines. 13 hours 5 minutes back. �778 single fare, �803 return fare).
Then take a bus from Bangkok Suvarnabhumi Airport to Bangkok Don Mueang Airport. From there you could take a domestic flight to an airport closer to Ban Dung, such as Udon Thani. (1 hour 5 minutes, �23 each way). Then possibly find a bus to Ban Dung.
Chris