A lean-to has a single sloping roof and the simplest form, ideal for bungalows, low eaves and tight budgets, and the easiest to keep within permitted development height limits. Victorian conservatories use a faceted bay end, which suits period frontages and gives a soft edge to a garden view. Edwardian and gable styles are square or rectangular, which wastes less floor area and takes furniture better.
P-shaped and L-shaped conservatories combine a lean-to run with a bay or gable end, giving two zones, commonly a dining area and a sitting area, under one structure. Choice is driven by the shape of the elevation, the position of existing doors and windows, and how you intend to furnish the room.