I left the house an hour early to do some scouting:
Pelawatta Ceypetco - Ballekwath nehe
Koswattha Laughs - Diesel closed, Petrol moderate queues
Baseline :
Ceypetco - Saw a container truck parked in front, so I'm assuming he was filling up both his tanks, however there appeared to be no queues for either fuel
The Laughs next door - Moderate to Darunu queues, spilling onto the Baseline, appeared to have both fuels from the looks of the demographics
Money shot:
Ethul kotte, smaller shed close to parliament road junc - 2-3 car petrol queue, no diesel queue, best to come from parliament road side since the road is narrow and 2-3 cars still spill out on to the road. I filled up from here, they said they received supplies in the morning and were fully functional.