If you need to get from Lake Bohinj towards the Soca river valley, you can take the train from Bohinjska Bistrica. The train goes through a 6 km tunnel and saves you a huge detour. If you have your car with you, you can load it to the train. You can just get off at the first stop of Podbrdo and drive in the narrow roads, between the villages of the valley. It's a beautiful drive, but a little tiring as the road is narrow and winding.
For more info on this special train, and special it is, see my MUST SEE/DO TIPS!
I can recommend this loverly trip to you!