I will be in Bled later this week and would like to take a bus from Bled to Bovec without going via Ljubljana. Will one be running at this time of year or is it too early? I am a bit scared of heights so don't want to hire a car and drive through the mountains and a taxi will be a bit out of my price range, so bus is really my only option. I really want to see the Soca Valley so any suggestions about doing that without hiring a car would be great, please.
I don't think there's an easy way of getting to Bovec this early in the season. The bus over Vrsic (stopping in nearby Lesce) won't start running for another month or so. You can catch a train at Bled Jezero to Most na Soci and then a bus to Bovec. However, it will be difficult to do sightseeing in the Soca Valley while relying on public transportation as sights are scattered all over the valley and the bus is only running as far north as Bovec until late June.
How about a guided tour? Or, you could still hire a car but simply avoid the mountain passes by taking the motorail between Bohinjska Bistrica and Most na Soci and then explore the valley by car.
However, both the road over Vrsic Pass and the road over Predel Pass are protected by guard rails and wide enough for two vehicles to pass over their entire lengths with very few exposed sections. I suggest you check them on Google Street View and assess whether you would be comfortable driving there. They are both very scenic.