Hi Carol, Tate archives at http://www.tate.org.uk/researchservices/researchcentre/archive.htm
most relevant to Fluxus in Britain is http://www.tate.org.uk/researchservices/researchcentre/archive_mayor.htm not much though.....the Jean Brown papers are the best for pictures also try http://sdrc.lib.uiowa.edu/atca/subjugated/cover.htm for Fluxus mail art documents, essays etc from University of Iowa cheers, Sol.
