I assume by home  page you mean "root level site". If the site  is a publishing
site you need to verify that the users have read  access to all the lists and
libraries required. In publishing they will need read access to the pages
document library, the styles library, the master page  gallery, the images
library, etc.

What error do the read only users get when they try to access the home page in
the root site? That may help  determine where the permissions  are lacking.

we had to check out and check in in desinger
then go to master page  gallaires then publish and approve it - it seems to help

Is thr any custom webpart deployed on home  page, that require admin
permission to run?