php to csv attachment – wordpress/woocommerce

I’m trying take this code, and make it generate / attach a CSV.

I have gathered from similar questions that i’ll need some strings like;

$csvString = "billing_first_name, billing_last_name, billing_phone, billing_phone, order, Product, Quantity, Price";
$attachment = chunk_split(base64_encode($csvString));

Once i’ve got my attachment generated, how to i add it to the email?

Am i correct in assuming it needs to be wrapped in php do_action() ?

This is the email template:

<?php
/**
 * Admin new order email
 *
 * @author WooThemes
 * @package WooCommerce/Templates/Emails/HTML
 * @version 2.0.0
 */
if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly ?>

<?php do_action( 'woocommerce_email_header', $email_heading ); ?>

<p><?php printf( __( 'You have received an order from %s. Their order is as follows:', 'woocommerce' ), $order->billing_first_name . ' ' . $order->billing_last_name ); ?></p>

<?php do_action( 'woocommerce_email_before_order_table', $order, true, false ); ?>

<h2><a href="<?php echo admin_url( 'post.php?post=' . $order->id . '&action=edit' ); ?>"><?php printf( __( 'Order: %s', 'woocommerce'), $order->get_order_number() ); ?></a> (<?php printf( '<time datetime="%s">%s</time>', date_i18n( 'c', strtotime( $order->order_date ) ), date_i18n( wc_date_format(), strtotime( $order->order_date ) ) ); ?>)</h2>

<table cellspacing="0" cellpadding="6" style="width: 100%; border: 1px solid #eee;" border="1" bordercolor="#eee">
<thead>
    <tr>
        <th scope="col" style="text-align:left; border: 1px solid #eee;"><?php _e( 'Product', 'woocommerce' ); ?></th>
        <th scope="col" style="text-align:left; border: 1px solid #eee;"><?php _e( 'Quantity', 'woocommerce' ); ?></th>
        <th scope="col" style="text-align:left; border: 1px solid #eee;"><?php _e( 'Price', 'woocommerce' ); ?></th>
    </tr>
</thead>
<tbody>
    <?php echo $order->email_order_items_table( false, true ); ?>
</tbody>
<tfoot>
    <?php
        if ( $totals = $order->get_order_item_totals() ) {
            $i = 0;
            foreach ( $totals as $total ) {
                $i++;
                ?><tr>
                    <th scope="row" colspan="2" style="text-align:left; border: 1px solid #eee; <?php if ( $i == 1 ) echo 'border-top-width: 4px;'; ?>"><?php echo $total['label']; ?></th>
                    <td style="text-align:left; border: 1px solid #eee; <?php if ( $i == 1 ) echo 'border-top-width: 4px;'; ?>"><?php echo $total['value']; ?></td>
                </tr><?php
            }
        }
    ?>
</tfoot>
</table>

<?php do_action( 'woocommerce_email_after_order_table', $order, true, false ); ?>

<?php do_action( 'woocommerce_email_order_meta', $order, true, false ); ?>

<h2><?php _e( 'Customer details', 'woocommerce' ); ?></h2>

<?php if ( $order->billing_email ) : ?>
<p><strong><?php _e( 'Email:', 'woocommerce' ); ?></strong> <?php echo $order->billing_email; ?></p>
<?php endif; ?>
<?php if ( $order->billing_phone ) : ?>
<p><strong><?php _e( 'Tel:', 'woocommerce' ); ?></strong> <?php echo $order->billing_phone; ?></p>
<?php endif; ?>

<?php wc_get_template( 'emails/email-addresses.php', array( 'order' => $order ) ); ?>

<?php do_action( 'woocommerce_email_footer' ); ?>