G'day David.
I'm not sure that I've correctly understood. I may have over simplified what you want to do. But here goes:
When I first started using Joomla, I caused myself much anxiety by trying to manipulate Joomla as I was used to with a hand coded html site. Joomla is quite different. You've just got to relax with Joomla and let it do things it's own way. Joomla's way is excellent!
Joomla will do what you want, nearly straight out of the box. That's how it's made. You may need a couple of plugins, as suggested by JLJ, to get the password protection and individual access, but that's about it.
Joomla has sections and categories.
So here's how I suggest you set up the site:
Section - South Coast
Section - Mid coast
Section - North Coast
And so on......
For every section you can have an Article Layout page which will be like a Mini Home page for that section.
You would also use an Article Layout page for your true home page. It would link to the Mini Home pages.
Now, leading from each section you would have two categories, more if need be. These categories would be Public and Subscription.
So your site hierarchy would run something like this:
Home
South Coast (mini home page)
Public
Subscription
Mid Coast (mini home page)
Public
Subscription
And so on.......
Now, I've already mentioned the Article Layout for the Home and Mini Home pages.
The articles in the public and subscription categories should be set out using the Blog Layout. Alternatively you could use the Blog List layout, but I'd go for the Blog Layout.
There would be other variations that you could use:
Instead of using the Mini Home pages as I've suggested, you could simply add a description to the top of each Blog Layout page and make it your Mini Home page.
I do suggest that you get yourself a practice Joomla installation and have a play for a while to get the feel of what Joomla will do for you.
Joomla really is the most versatile thing they've come up with since the invention of the T-shirt.
So please feel free to make what you will of my suggestions. Hope I understood correctly.