I have built 3 websites in the last 18 months, with 1 more almost finished. All are online gallery style sites, built using HTML and CSS. About 1200 single image pages, accessed through thumbnail pages (max 30 thumbnails per page), built with Expression Web and Coffecup software.
We have only satelite internet connection, so I am not sure of page/image loading speeds in the real world. One site is www.photographsindigenousaustralia.com , the others are linked to it.
Should I be using the preload images behaviour for the thumbnail pages, or does Coffeecup have software to speed up page laoding. I think I got an email from coffee cup promoting something similar?
I am very much an amateur beginner and I would appreciate your advice

There are some tools that can help you to improve the page load speed. I'm using Google's PageSpeed Firefox extension and http://www.webpagetest.org/

From what I see, your pictures are loading quite well. And I think that the loading time for such a website isn't so big issue, because the interested public will always have the patience to wait a couple of seconds in order to view the pictures. This is a normal behaviour for the users browsing such websites.