Hi Ash, the son of GOD, or possibly ROG! 
It sounds like someone is a bit nervous about being throw in a Manual
After passing their test in an Auto! 
(Maybe you should have had a 4th instructor in a Manual as well…
)
But joking aside, it’s something I’m nervous about, as I’m taking my test in an Auto in a couple of weeks time with PSTT. You’re probably thinking the same as me “I’m used to a clutch, so how hard can it be?” or “Should I have learnt in a Manual?” which I bet your feeling now, as judgement day is almost upon you! 
But I think it’s worth remembering that DHL will know your a new pass, and won’t necessarily expect you to be familiar with the truck, so I suspect (and hope) you will have a bit of a free pass, to ask newbie questions. However grinding every gear before you get out the gates, may result in a very short employment period! 
Have you seen dieseldaves post on “Introduction to a couple of 8-speed gearboxes WITH PICS…” here: Introduction to a couple of 8-speed gearboxes WITH PICS - NEW AND WANNABE DRIVERS (INTERACTIVE) - Trucknet UK
As for hours, what makes you think you’re going to spend your whole day driving and not doing “Other Work” or possibly “POA”. I’m sure someone will be along who has worked for DHL who can fill you in. And there looks to be a few threads in the main forum about DHL…
Best of luck and give us the bowel clenching details of how you get on…
Al
P.S.I don’t think nick2008 is trying to put a downer on anything, just being brutally honest! I’ve been on this forum a while, as i’m a bit ■■■■ about researching things before I do or commit to them, and from what I’ve seen on here, your probably going to be on physically demanding “cage or handball donkey” work, that you may like, or hate in equal measure. I think it’s considered “undesirable” work, and possibly why a lot of people want to get straight to C+E. Personally, I think that while this isn’t necessarily a job I would want to do long term, that isn’t important! The only thing that matters is getting that 6 months experience under my belt, which opens up better opportunities. However I wouldn’t suggest you say that in the interview, and suggest you go with “This is the job of my dreams!”

The interview is all about a positive attitude! i.e. Getting fit for free is a perk of the job! 