All depends which depot you have got a job at? I worked for HH for 5 years, 66s are dirty, cold in the winter, boiling hot in the summer (I understand that some are now being fitted with Air con) and very very noisy! There could be a lot of van driving, also train preparing and shunting, so at some depots your not just a driver.
The diagram lengths are between 6 and 12 hrs, the link I was in was 20 weeks if I remember there were about 12 weeks of nights, lots of 23.00ish working 11hrs 30mins plus!
Biggest problem at HH and its been the same since they started there operation is the rostering, however if you are going for the cash and you can handle the shocking shifts and dodgy rostering you are going to work for the right FOC!
If you want any more info pm me, and if I don't the answer to your question and know lots who will. Cheers