After reading back through the posts I found and tried this code for login.php and it works
if ($login_type == "C" || $login_type == "B") {
if($redirect2 == "checkout")
func_header_location($redirect_to."/cart.php?mode=checkout");
elseif (!func_is_cart_empty($cart)) {
if((strpos($HTTP_REFERER, "mode=auth") === false) && (strpos($HTTP_REFERER, "mode=checkout") === false)) {
func_header_location($redirect_to."/cart.php");
Thanks,
Louise