From Billund airport fly to Copenhagen airport. 50min $110. From Billund Lufthavn line 44 bus to Esbjerg st, train to Odense st, then train to Koebenhavns Lufthavn st. 5hrs 12min $78. From Billund drive to Kastrup. 2hrs 48min $60. From Billund taxi to Give st, train to Herning st, taxi to Karup airport, then fly to Copenhagen airport. 3hrs 29min $223.