I'm sure that there is one on a posting in
http://www.seatcupra.net - and probably a part number - I always thought that it was misleading as it is a mirror image of what you might expect, I seem to remember starting to make a drawing up for future use - but I can't remember if I completed that with actual fuse functions and values or not! (seemed like a really good idea at the time!!)
Look for the fuse layout under Ibiza Mk4 FAQs section - its still there but not in the original posting - its further down.