Thanks for the reply,
So I set the go to page to contact.php then clicked the lightning icon to go into the select data bindings dialogue. I'm not sure though how to pass the querystring variable you mentioned. The following code is in the code field:
<?php echo((isset($_POST[""]))?$_POST[""]:"") ?>
Do I go:
<?php echo((isset($_POST["page.php?sent=true"]))?$_POST[""]:"") ?>
Sorry, still trying to learn php syntax.