A workbench is a useful addition to any greenhouse. You can use it for raising seedlings out of the reach of ground-dwelling pests, for potting on without bending, and for keeping small tools and pots in an orderly way. There are free-standing versions available or you can use a small table, both of which impact on growing space. In a large structure this isn’t a problem, but in an average small greenhouse it can mean fewer tomatoes, salads and strawberries.
A folding bench is a good compromise: it can stay open in the spring when propagation is at a peak; or you can fold it up when not in use and grow plants in the soil underneath.