If you have a meter enclosure installed that has triple barreled lugs on the load side you would have no problem running the additional service entry conductors directly to your pool house.
The other approach would be to install a four hundred ampere, main lug only, 3R raintight, twelve slot panel, that is suitable for use as service equipment. By installing that panel adjacent to the meter enclosure you could have a beaker for each panel including the one in your pool house. That would be a much more expensive approach however. It would also require a partial rewire of your two existing panels to separate the neutrals from the Equipment Grounding Conductors.
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison