So you want to get the table name that is declared in the xml and you are not in an upgrade/install script.
If you were in an upgrade/install script you could just use:
$tbl = $this->getTable('catalog/product');
In any other page you can use:
$tbl = Mage::getSingleton('core/resource')->getTableName('catalog/product');
If this will return: catalog_product_entity
This works with any declaration that is set in the xml!