Hi Upekkha,
This is the link to the Youtube channel; https://www.youtube.com/channel/UCpA0sy3c2kTFKmiUaLElFfA
Most of the sermons are in Sinhala but there are a few in English as well. The English sermons are conducted every Sunday afternoon (at around 2 or 3 pm) Sri Lanka time and is streamed live on the YouTube channel.