Congratulations on getting on the course, it's a great job and I'm sure you'll love it.
With your location I'm guessing your course will be in Manchester so can't help on that but I can't imagine it'll be to dissimilar to mine when I was in Leeds.
It's Mon-Fri, 9am-4pm ish there will likely be days when you finish early.
You'll learn all elements of the railway eg signalling, track safety, emergency protection, dispatching etc etc but the trainers are very good and the course is designed to get people off the street with no experience upto competent conductors.
I've not seen it personally but there are definitely instances where people have been kicked off the course for a variety of reasons. It shouldn't be a worry though, if you put the effort in and have the correct attitude you will be fine.