When it comes to expressing the idea of having something at your disposal, there are a number of useful synonyms to choose from. For example, instead of "have at disposal," you might say "have available," "have access to," or "have on hand." Other options include "possess," "hold," or "control." You could also use phrases like "at one's fingertips," "within reach," or "within easy reach." The key is to choose the word or phrase that best captures your intended meaning and fits the context of your writing. With the right synonym, you can communicate your ideas clearly and effectively, and make your writing more engaging and impactful.