There have been two Van Morrison fanzines that I know of. Sadly, both are now defunct. The first was called The Van Morrison Newsletter and the second was called Wavelength magazine. The Van Morrison Newsletter was edited by S. McGinn from Clydebank in Scotland. When it finished up in the early 90s one of its contributors, Simon Gee, established Wavelength and continued to write about Van.
Wavelength developed into a really substantial publication for the Van fan. I was never a subscriber but have bought my copies latterly on ebay. A copy of Wavelength sells for something like $10 to $20 with the postage. The Van Morrison Newsletter is much rarer on ebay.
A number of Van fans from all over the world contributed to Wavelength. A standard edition had about 60 pages. Wavelength finished up some time in 2008. Information from Guenter Becker's Van Song Database site says that the Wavelength website that was "shut down due to activities by John Giacobbi on behalf of Mr Van Morrison". Simon Gee appears to have gone onto some other jobs in music.
I think all Van fans are hoping for a Van Morrison fanzine to be resurrected soon. Or maybe Simon Gee will publish some books or booklets based on the unpublished items and files he must have accumulated in his time at producing Wavelength.