Ah, the Lake District, one of the best places for scenic bus routes and challenging drives.
77A at Portinscale
Yes buses go up the Honsiter pass, it is impressive.
555 in Ambleside, a 3 hour journey from Keswick to Lancaster
I don't know how good your eyesight is but there is a bus in this image
This is a challenging one, good luck (I just wanted to show you the good views)
I might make a video of some recordings of my trip on the 77 but it's not the best thing you've ever seen and it started raining half-way through.