I've been told buy an ex bus driver, that once you've got your bus licence you're able to drive a bendy bus, there is no bendy bus specific licence, unlike HGV's, my daughter is taking her class 2 which will allow her to drive anything over 7.5 tonne and rigid, if she wanted to drive artics she would need to take her class 1, I would argue that a bendy bus behaves very much like an artic and would take a fair bit of skill to drive safely.