Can´t you learn English via Duolingo?
Yes. At the moment the only option is to finished learning Spanish, and you can then use that to learn English, but I guess that isn't too helpful for you!
I think it would be useful if there was a learn English from pidgin option, but I guess that won't happen any time soon. We could then be set translations of all those incomprehensible instruction manuals and foreign tourist websites already written in bad English.