You'll probably be asked about the company, traction, routes, etc. out of whichever depot you've applied for (I'm guessing Plymouth from your location). How do you feel about/can you cope with shift work, working alone for long periods, the amount of learning involved, etc. You'll get some "Can you give me a time when....." type questions most likely. You might get some about non-technical skills for drivers.
Hope this gives you an idea.
All the best.