If you read this forum you’ll see many new drivers struggle to get a start, somebody’s given you a start so you should take it.
It’s unlikely to be the best job in the World, but it’s a start, a stepping stone, we all had to take them and then build the experience and start looking for the next move.
And you never know, once you get into the grove of the job you might enjoy it.
To the OP
Its a start so go with it.
They can always replace a driver you can’t replace your licence so look after it no matter what some idiot desk jockey says.
To start with you’ll probably be covering other folk’s runs but you’ll get your own eventually
Parcels can vary hugely depending on the depot and the run you’re on. I covered a 7.5t round the Lakes for a few weeks, loved it except for the PITA which is Sellafield, long days and part of the secret is to organise the packages as best you can beforehand, I found it was hanging around for some of the collections that screws the day up.
Doing collections in an 18t was good fun and a lot more varied and interesting than trunking up and down motorways.
In my experience Fedex and TNT run good legal kit though carrying some spare 24V bulbs, little multi-bit scewdriver is a must for any driver and I reckon a decent rucksack makes the best driver bag for carrying your gear unless you’re tramping. Maps and stuff will depend on the area you’re covering, A-Zs for urban, OS maps for rural and if you can afford it a good trucknav (used with common sense) is very helpful