You could try using ready coconut milk/ coconut milk powder. Dilute with some water if too thick. But make sure its of good quality as it is the main taste of this dish.
To extract thin coconut milk, add 2 cups water to approx 1 cup fresh grated coconut & blend in a mixer. Then strain through a sieve to extract coconut milk of semi thick consistency. Adjust water & the coconut quantity as required. This is only an approximate.