i sowed them indoors though, in april
Unless your house is warm all night though, it is still cold at night. I know it is annoying but French Beans are very tender indeed. In April, even if warm enough indoors to germinate, they need light and may grow too long to be sturdy enough once they go outdoors.
Marigolds - all marigolds give off pheromones that can keep pests away - but the French ones are the ones that are used for companion planting mainly. If in doubt, any marigolds will do.