I live in Holland near the city Leiden. I fly at a naval airforce base so taking a look at the place where I fly will be a bit difficult.
I don't know a lot of hobbyshops but you can take a look at http://start.modelvliegen.com/
But I'm afraid it's in Dutch. Look at "Modelvliegwinkels" for hobbyshops in Holland.
Clubs can be found at http://www.airtoi.com/
It's a bit difficult to navigate on this site but i'll try to explain.
-Click on "Clubs" (top bar)
-Click on "NL + B" (Holland + Belgium) in the left menu bar
Now you can do a search for clubs. You can select a part of Holland where to search at the "provincie" pulldown menu. Leave the text "allemaal" in the "clubnaam" menu.
- Now click "start zoeken" et voila. A number of clubs will appear.
Good luck and enjoy your stay in Holland,