Bus driving is very convenient in Sri Lanka. A ticket usually costs less than 1 euro. On our trip we took a bus for the route from Ella to Udawalawa. We had to change into another bus line on the way and this worked without great problems and long waiting times.
The easiest way is to ask your staff to ask which bus you should take. Then you can go to the bus stop with a tuk tuk and get on the bus. From the finish line, you can take a tuk tuk to the final destination.