In a small bowl, combine the mayonnaise, lemon zest, lemon juice and fresh dill. Spread the lemon mayonnaise over 1 side of each slice of bread. Arrange the smoked salmon on 4 slices of the bread.
Break up the bacon and put on top of the smoked salmon. Top the bacon with rocket and arrange 2 to 3 tomato slices on top. Cover with remaining slices of bread, lemon mayonnaise side down. Arrange the sandwiches on a platter and serve.