Manmatha Nath Dutt's translation of Uttara Kanda is also available on archive.org here.
- Ramayana-VOL-4-Uttara-Kanda.pdf (scanned copy)
- Ramayana-VOL-4-Uttara-Kanda_text.pdf (OCR-converted to text, so you can search the contents)
If you are looking to buy a book, try the 2-book English tr. from Gorakhpur Gita Press. But right now it's not listed on their website (out of stock maybe) so if you are physically located in India try buying it from one of their stores. Athough it lists the original Sanskrit verses, it is not a word-for-word translation. But it's a complete translation of all 24,000 verses including the Uttara-kāṇḍa.
This is how it looks:
Shrimad Valmiki-Ramayana, Sanskrit Text, English Translation, Volume-1 (Book Code: 452)
Shrimad Valmiki-Ramayana, Sanskrit Text, English Translation, Volume-2 (Book Code: 453)
Here's a sample.