99% of container work is on a C+E licence (Class 1 / artics) so that`ll be a fair commitment on training. A lot of newer licence holders on C licence (rigids) seem to start on multi drop shop stuff. That can involve pulling around a pallet truck or cages of goods over uneven pavements etc. Maybe not too easy.
So, it could be a case of jumping straight in for you, rather than taking it in stages? Good luck, whatever you decide.