Hi,
I German and a member of the above mentioned lowcarb board (offical URL: www.lowcarbforum.de), which is IMHO the best German LC board. Of course it is in German, but it has almost any information about LC and I don't think you won't have problems, if you post a question in English there. The people on the board are extremely kind.

In Germany you cannot buy Atkins products in local stores and there are only a few online stores with LC products:

www.supermass.com
www.low-carb-shop.de
www.lowcarbladen.de

Unfortunately the prices for special LC products are terrible. Therefore most people don't use any of them, but for example bake their own LC bread (me too). There are fantastic recips with German products to be found in the subforum "Rezepte".