Stayed at the hotel until one minute before checkout time. Checked out and left my big bag there while I went to lunch and killed time at KFC until 14:00.
The train to Colombo left a little before 15:00 and arrived at Colombo Fort station at 17:30.
I found the airport buses at Map Location: 6.934312, 79.848812 , and confirmed that they ran all night.
I walked over to the BK about a kilometer away and had dinner and killed a few hours there.
A little after 19:00 I took a tuk-tuk back to the airport buses and headed to the airport. The bus took almost two hours to get to the airport