I don't know which would provide "greater benefit" for you, but I think it would make sense to get the camera first. You are planning on getting both. The camera is going to take a fair amount of time to learn to use (it is a noticeable upgrade from your current camera), and you can spend the summer getting comfortable with using it. While there is definitely a learning curve for a UWA lens (and I think it would be a terrible choice for using in a nightclub -- people on either side of the photograph are going to look fat, which a fair number of people find off-putting), the degrees of freedom are substantially fewer than with the camera body. You should be able to get a reasonable sense of how to use (and not use) the lens after a few outings with it, but the camera is going to take all the time you can devote to it this summer. Or so ISTM.
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