Katora lake is not in kumrat valley it is on the boundary of kalam and upper dir.
kumraat valley starts from thal village in upper dir. both are opposite to each other, yes, to reach both kumraat or katora lake, you must have to reach thal village which is approx 6 to 8 hours ride from upper dir bus station. if you want to visit katora lake, ride up to right side for the village of jandri, and for kumraat valley u must go left side if comming from upper dir.
thal is also accessible via jeep from utror (kalam)
from katora lake you can reach utror crossing dir gali in 2 days trek.