Runs are usually made up of about 3-5 drops, but I average 4. I’m based at the Coventry depot. Head Office is Hemel Hemstead. I think their area covers London, South East Anglia (Below and including A14), South East UK and some other bits.
Basingstoke depot covers South Coast from M4 down to Portsmouth and across to Cornwall, around Berkshire and Oxfordshire. Yeah, more bits. This is a rough guide.
Heywood depot covers north of Cheshire and Yorkshire.
Coventry covers Midlands, South & Mid Wales, some Gloucestershire, Staffs, Derbyshire, Sheffield, Rotherham, Scunthorpe, Skegness and Lincolnshire.
The trucks carry barrel boxes that the stores use to recycle products. They come back along with some cardboard and bagged drinks containers. All in cages. We deliver in cages, and bring the empty cages or ‘reverse logistics’ back. We also collect oil for recycling. You’ll notice that our trailers have two belly tanks. One is for red diesel for the fridge. I’m sure you can guess what the other is for 
The office provide risk assessments and ‘recommendations’ on where to deliver. They’re not all flat, and the trailers can only level off using the trailer/trailer air controls. Alas not side to side, but if they could, that would be awesome!!!
Buns, Dry, Chilled (2-4c) and Frozen (-18c) are the sections transported. At each delivery you would work out the trays of the buns, and the cages are labeled up and we’ve handheld scanners to log them off the truck.
They don’t drop you in the deep end. Once you’ve got the interview, passed and got the job, you get training on the way it works, then get buddied up with trainers or drivers to see how they do it and and how deliveries work. 3 days in the classroom doing paperwork and that side of learning, then a week in training on the road.
Some stores we drive straight in, screw around in the carpark and backup to the delivery doors. Some we have to reverse in from the main road, a side road, drive around the store to line up, park in a side road.