I think it's pretty widely accepted that TDD is not a good fit for UI development. What is important is ensuring that there is a clean separation between the UI

I think it's pretty widely accepted that TDD is not a good fit for UI development. What is important is ensuring that there is a clean separation between the UI and any operational code, such that the operational code can be unit tested in isolation. Then frameworks such as Selenium can be used to focus on testing the functionality of the UI. But, as you indicate, automated testing of UI look-and-feel is not trivial.