Hi,
This is a very broad question, and the answer probably depends a lot on your environment.
I'm not an admin, but I would start by thinking about how your DEV and PROD environments are set up (and distinguished). Then I would think about making the same changes for UAT environment.
As a simple example, I only have access to one server environment (sadly), so I use directories for /DEV, /TEST, /PROD. And I have a macro variable &mode which resolves to DEV | TEST | PROD. So if I were adding UAT, I would need to create the directory branch for /UAT (in OS directories and metadata directories).
So if if your DEV and PROD environments use different host names, then I would think UAT should also have its own host name.