Actually, I finished laying a solid oak, 3/4 inch thick prefinished floor a few months ago. In this case it was, of course, here in the U.S. and the brand was Bruce, however there are many prefinished oak (or other woods for that matter) floors. The finish is usually a stain and several coats of Polyurethane covering.
I'd say find out the brand name form the installer. They will be able to provide a "kit" that includes some coloring matching your flooring as well as instructions on how to apply. You will find, however, the scratches, ordinary wear and tear and other daily use is actually one of the charming thigs about a wood floor. If you expect it to remain pristine for very long, given kids, dogs and the ability to drop things, one shouldn't choose hardwood flooring. When the whole thing gets to the point that you really can't stand it anymore, you'll be able to hire someone (or DIY if you choose) to come in and sand it with a machine and refinish.
Best of luck!