Ideals about helping new drivers get a start is very admirable, one OD here tried that and had his fingers badly burned as a result, i’d be careful indeed.
My only input on this is as a driver, i gained a O licence many years ago but never used it (personal circs, but overall i did ok without going OD so no regrets), is to be careful of what work the used lorry you might consider has been on before, 500k of running round with parcel weight on board on motorways is a hell of a lot different to a vehicle thats had 44 ton on its back run night and day on all sorts of terrain with every tom ■■■■ and batvol at the wheel.
Full R&M is great, but don’t get carried away with the idea it means no troubles, these new lorries arn’t proving durable if the work is hard (Scania probably the best bet but at what premium?), will the dealer definately have a suitable vehicle for you to use whilst yours is having its 3 time a year several days visit to fix the latest issue? with one lorry you haven’t got any clout at the dealership either, if your vehicles fill 1/3rd of their bays all week its a different kettle of fish.
As a driver i’ve found the old square Merc Axor especially with the 430 engine coupled to a manual box to be as good a work horse as you will find anywhere, very durable long term, and should be cheap to buy used because it lacks kudos, badge kudos doesn’t pay the bills.