I've been there last year. There's not too much to skate. They have a small scene in Colombo. I think the shop they had closed doors. I heard people would meet up at the racecourse to skate, can't remember what day, though. I think it was Saturday or Sunday. There was a small DIY pool near Midigama beach (close to Weligama)
We did a round trip, starting from Colombo. We did stops in Galle to check out the fort, near Weligama to go surfing, Udawalawe national park, Ella to do some hiking, Nuwara Eliya and Kandy for some culture.
We did most of the trip by train which i would recommend as you can see some real nice scenery out of the train.
If you need more details let me know.