Uttara Kanda in Ramayana details the story of the separation of Ram and Sita from birth of their sons. Uttara Kanda also details the story of Luv Kush – sons of Ram and Sita. You can download and read Ramayana Uttara Kanda in pdf for free. It is provided by Gita Press.
The text is divided in two parts.
Link - English Uttara Kanda of Ramayana - Part I
Link - English Uttara Kanda of Ramayana - Part II
Link - English Uttara Kanda of Ramayana - Part I
Link - English Uttara Kanda of Ramayana - Part II