In a mixing bowl, combine the softened cream cheese, chopped dill, chives, lemon juice, salt, and pepper. Mix until smooth and well combined.

Using a sharp knife or a mandoline slicer, thinly slice the cucumber into even rounds. Pat the slices dry with a paper towel to remove excess moisture.

If desired, lightly butter one side of each slice of bread. Spread a generous layer of the herb cream cheese mixture onto the unbuttered side of four slices of bread. Arrange the cucumber slices evenly over the cream cheese, slightly overlapping if needed. Top with the remaining slices of bread, buttered side out.

Using a sharp knife, carefully trim off the crusts from the sandwiches. Cut each sandwich into quarters or smaller triangles for a traditional tea sandwich presentation. Serve immediately or chill in the refrigerator for up to an hour before serving.