Thanks for suggestions, I got pointed in the right direction by our support company, it is the same as in moodle 1.9 you just need to know where to look.
You need to go to Course Administration > Users> Permissions (actually click on permissions, don't use the drop down)
Use the "Advanced Role Override" drop down, and pick "Authenticated User".
You need to find this permission (I suggest searching for it, its a long way down).
View courses without participation
Change this to allow, and Save changes at the bottom.
Hope this helps.
It was the bit about just clicking on permissions not using the drop down which had thrown me.