I forgot to add the buildout snippet to create the directories:
I had to use this:
recipe = collective.recipe.filestorage
location = var/filestorage/Data%(fs_part_name)s.fs
zodb-mountpoint = /%(fs_part_name)s/mnt:/db/mnt
blob-storage = var/blobstorage-%(fs_part_name)s
I added this to the end of my 'parts' list:
recipe = plone.recipe.command
alldirs="`ls -d blobstorage*`"
for i in $alldirs; do
This then makes all the 'blobstorage*/tmp' directories that are required for uploading images.