Sæl Alfta!
 
I have searched for an English translation of Ljós Heimsins in the British Library catalogue, the Library of Congress and COPAK (which is a research library) and none have come up with an English translation.  According to our university librarian, these are the three biggest libraries in Britain and if there were a translation in English the chances are one of them would have it on record.  (However, I did find a Greek translation and a Dutch one!)
 
The only other possibility is that a translation was made and published in Iceland and never distributed abroad, so maybe it would be wise to check with the Library of Iceland.
 
Other than that, I think it would be safe to recommend this to your volunteer.
 
All the best,
Sarah.