Woocommerce Custom Checkout

You can create a custom page and add that custom page url in below function. So all WP “Proceed to Checkout” will go to the custom page.

And in that page you can have a link to Final Cart Page and add the checkout link there.

add_filter('woocommerce_get_checkout_url', 'wpse_redirect_checkout');

function wpse_redirect_checkout($url) {
    global $woocommerce;
    $checkout_url="http://www.example.com/custom-checkout-page";
    return  $checkout_url; 
}