There is also a karma kagyu retreat centre in Poland:Drubkhang
I don't know anything about processs of being accepted there, though.
You have to apply either to Kyabje Tenga Rinpoche personally or to Polish Lama Rinchen who will then talk to Rinpoche about it.
The next retreat starts in 2013. Kyabje Tenga Rinpoche and Kyabje Sangye Nyenpa Rinpoche give all the Wangs and Lama Rinchen and Lama Mingyur Sönam are the Drubpöns of the retreat.
Its the leasr expensive 3 year retreat I know about in Europe.