The Apocrypha Index
http://www.jesus-christ-forums.com/arabic_bible/apocrypha.php
The Epistle of Barnabas is in there but not the Gospel of Barnabas.
The Muslim scholar Cyril Glassé states about the Gospel of Barnabas:
As regards the "Gospel of Barnabas" itself, there is no question that it is a medieval forgery. A complete Italian manuscript exists which appears to be a translation from a Spanish original (which exists in part), written to curry favor with Muslims of the time. It contains anachronisms which can date only from the Middle Ages and not before, and shows a garbled comprehension of Islamic doctrines, calling the Prophet "the Messiah", which Islam does not claim for him. Besides its farcical notion of sacred history, stylistically it is a mediocre parody of the Gospels, as the writings of Baha'Allah are of the Koran.
The Concise Encyclopedia of Islam, Harper & Row, 1989, p. 64
Here is some more information on it!
http://www.chrislages.de/barnarom.htm