This is free android app that comes handy when you get into such situations. This one requires INTERNET connection to pull the data from server. This has a simplest tamil keyboard which you can easily type and the right english words.
The app can also be an enabler for you to teach english your self during free time. You can type vegetables, animals, fruits, body parts etc in tamil and get the right english words.
I hope this would bring you better experience, I need your feedback to improve this further.