I only have experience in C++, but the concept should be the same.

Try echoing a space between the variables.

Code:
<?php
$body1 = $LeadFirstName;
$body2 = $LeadLastName;
echo ($body1);
echo ' '
echo ($body2);
echo ' '
echo 'Thank you for registering.  Your free ebook will be emailed to you within 48 hours.';
?>
_________________________
"We can categorically state that we have not released man-eating badgers into the area."

-UK military spokesman Major Mike Shearer