Trim Tab Effect On Pitch control?
 

if an aircraft has an automatic tab that also acts as a trim tab. What affect would trimming have over flight control travel?

None,as both control surfaces and tabs(either fixed,adjustable or balance) have their own specific range of travel....

The total travel RANGE would not alter. However, the mid datum position (the trim point) will have moved so the travel from mid point to maximum will be more in one direction and less in another.