If one needs to use the loo during a meal, don’t announce your intentions. Simply say, “Excuse me,” and leave it at that. (That’s also the phrase every parent should teach their child.)
If one is not finished eating they're meal cross the utensils so wait staff know not to take the plate.
When finished with the meal, they place utensils at an angle, putting the handles at the bottom right of the plate (like 4:20 on a clock).