Sony has stated that Europe will get 1 million units in the launch "Window". I'm not sure if they've clarified how large that window is though.
Well ... When companies talk about "Launch Window Games" it usually means games released within 6 weeks to 3 months ...
The way I see it Sony will attempt to get the most press out of the European launch as they can. They will need to say they have the largest single day revinues (the price of the PS3 makes this a lock), they will need to sell out, and they will want it to be the largest number of units sold at launch ever; I would expect Sony to release the lowest number where they can (successfully) make these claims.