To a very great extent, adjusting to crop failure depends on the personality of the individual forced to make an adjustment. We will get specific.
After the cataclysms livestock will die for lack of feed or be eaten. Seeds sown will fail to thrive after germination from lack of sunlight and the excessive drenching rains. What will the survivors eat? Those who have prepared by establishing intensive indoor gardening such as Hydroponics and the most protein efficient animal husbandry, Fish tanks and ponds, will find themselves not only subsisting but subsisting well. Such arrangements require indoor lighting. Hydroponics can be grown around the clock and fish eat either this produce or water plants that feed off the community's Sewage Effluent, but the base of this food chain is the hydroponic vegetation. For plants, light is life, for without it plants die. Such indoor farming, in place prior to the cataclysms, should not rely on lighting from either the Sun or the utility companies. Both will in essence go out during the decades immediately following the cataclysms. Power for indoor lighting should rely on harnessing wind, or water flows, or other such mechanical generation that can be counted upon to be present after the cataclysms.
Food stuffs that can be grown without artificial light and will do quite nicely on the gloomy light supplied by the Sun are mushrooms, earthworms, and various insects that feed on dead tissue. After the cataclysms bugs will be in abundance, as dead tissue from both plants and animals is everywhere. This trend can be taken advantage of, as distasteful as that concept might be to humans who have never eaten a bug. Larva, grown in humus, can be turned into pureed and creamed soups, puddings, or omelets by skilled cooks. Those eating the fare would never guess that the base was not cream, milk, and eggs. For those humans who do not prepare, they will find themselves Eating Bugs in any case, as meals from what they can catch or find growing will be few and far between.