thank you so much Mary
For others the problems for me was a corrupted guest password. Opening the database table mdl_users (very scarey but it worked) clicking the pencil next to the Guest user row, opting for the MD5 option in the left box and typing guest in the password box next to it, then Go at the bottom and it works like a dream.
Courage mes braves - problem of no guest access solved and NOTHING to do with versions either
Mary again - thanks so much this has been bugging for days