You can go to Operator > UK operator > Access rights > restriction to information found in sub folder.
This way you can give access to one folder. Else you will have to go with way i explained in previous answer. But creating group for each locale and then adding that operator group to folder permissions.
I have main admin which can able to access all the folders and have RWD access(All folder including inside Admin & Config folders) as well. I have custom admins under main admin for two business folders ie UK and SG. UK admin can have RWD access (All folder including inside Admin & Config folders for UK) for UK alone not for SG region. Likewise SG admin does.
Under UK folder, A recipient can access only campaign folders not for all. Likewise SG folder as well.