They don't want their users to see this screen becuase information can be edited. If the confirmation form can be submitted automatically, then the users can use the booking system.
I use an "invisible form" in a Content Management System I developed, and usually looks like this:
<form name="return" method="post" action="<? echo $some_url?>">
<input type="hidden" name="id" value="<? echo $id?>">
<input type="hidden" name="mssg" value="<? echo $mssg?>">
</form>
<script language="JavaScript" type="text/javascript">
document.return.submit();
</script>
Thus, the form is automagically submitted without the user knowing what is going on.
If that booking system is developed by you or this client of yours (and considering I understand correctly what you need) I would suggest setting a cookie and if it exists, then skip the login page.