if you drive from Lake Bled to Logarska dolina (dolina means valley) you have a few options. First one is to take the highway towards Ljubljana and take exit number 8 / Kranj - zahod, direction Kokrica/Preddvor/ Zgornje Jezersko. It's about 90 km or 60 miles to Logarska, but the road is winding, and when you come to Zgornje Jezersko you will ascent towards Austria and after half an hour or so you'll be back in Slovenia. You will also reach Pavlicevo sedlo pass (4390 feet). After that you will start to descent towards Logarska dolina. It's about 15 km or 9 miles. When you come to Logarska, you will need to turn right (there are signs, no worries). There's a small entrance fee ( 7 € per car). Driving on this road is not a problem during the summer but it's a bit different in the winter.
Next option from Lake Bled is to take exit 11/Vodice/Cerklje/Kamnik. In Kamnik follow the signs for Gornji Grad. You don't go as far as Gornji Grad but will need to follow the signs for Podvolovjek/Luče when you get closer to Gornji Grad. When you reach Luče just follow the signs for Solčava and Logarska dolina (from Luče it's about 10 miles to Logarska dolina). This road is a bit difficult to navigate because it's a local road and some parts of it can be confusing for tourists.
Third option is to take the highway all the way to Ljubljana and when on the ring road (bypass) just follow the signs for Maribor/Celje. From Lake Bled to Ljubljana you have 35 miles. From Ljubljana you have about 45 miles to Mozirje. You need to take exit towards Sentrupert/Gornji Grad/Mozirje. You continue on this road for about 60 km or 40 miles to Logarska dolina. There are signs. You will pass towns of Mozirje, Ljubno, Luče, Solčava. This is the longest but also the easiest way, around 75 miles from Ljubljana. The road for the last 40 miles is a bit bumpy in places, but nothing to worry about. Very nice scenery, lot of places to stop, gas stations are in Mozirje, Ljubno, Solčava. If you need food or drink, you can all buy at the gas stations or stop in Mozirje or any bigger town. You'll get all you need. There are no gas stations in Logarska dolina.
I hope this will help. If you have any other questions about your trip in Slovenia, don't hesitate to ask.
Dejan from Slovenia