So i have chronic urticaria and my c u index was 38. can this make you more sensitive to the sun?

Maybe; see allergist: People with chronic urticaria get hives randomly and spontaneously, usually NOT in response to environmental exposures. But sometimes things like warming the skin (e.g., sun exposure) can bring out hives; you just have to try it an see. High-dose antihistamines are often helpful at preventing hives, but there is an injectable medication that works well, especially with a positive CU index.