I already ordered some rosco from http://www.RSTdistribution.de ( or http://www.castinfo.de ).
As ElkMonster said, just call them. They usually use the uk catalog. Very nice people, i must say.
They can get everything from the uk catalog. They don’t always have everything in stock, but will order it with a bulk order from uk.
You can also order from uk directly through them, but thats extremly expensive (would have been around 50 euros postal charge from uk, in my case (two sheets of rosco) ).
So i saved the money and it’ll take about 2-3 weeks. don’t care bout that.
First called them and had a little chat, than i sent an email with the order and shipping info. They’ll send you the order and payment details.
It’s not the kind of mass products there, so i can understand they don’t have an online shop.
But as i said, nice people to talk to.