In git, there is no "one way" of managing the code workflow, and you should use what suites your inner workflow best.
On atlassian web, there are several workflow types compared. In the section "Hotfix branches" of page "Gitflow workflow" (that seems to be best for you) is shown, that you should merge the hotfixes right away into master and develop branches. It is based on workflow defined by Vincent Driessen at nvie
Then it is obvious the release (or in your case UAT) branch should come from develop branch