Ade,
Your best bet would be to ring Matej or email him:
fauna@faunabled.com
The Trout season is coming to an end but dates vary in different parts of the river. Grayling is longer.
On that day they were all Rainbows but the day before, all Browns...don't ask me why..they are equally distributed on the river! The bigger fish are deeper but if you want a load of fun put a spider on and catch Brownies at about three to the pound..they go absolutely berserk
There is apparently some superb Grayling water down near lake Jezero but again, they are pretty well all over the river. I saw a chap take an absolute stonker right where I had been catching Browns all day.
We flew EasyJet from Stansted to Lubliana which is about an hours easy drive from Bohinje or Bled. I don't think you can get there from anywhere else, at the moment.