You could do this a lot easier in one of two ways....
1) Use Server-side-includes to run your PHP.
In your html file:
<!--#include virtual="/path/to/script.php"-->
In your httpd.conf:
<VirtualHost yourdomainname.co.uk www.yourdomainname.co.uk>
ServerName www.yourdomainname.co.uk
DocumentRoot /www/vhtdocs/yourdomainname
AddHandler server-parsed .html
</VirtualHost>
OR...........
2) Change your VirtualHost config for the domain you're concerned with to make .html files run through the PHP parser....
<VirtualHost yourdomainname.co.uk www.yourdomainname.co.uk>
ServerName www.yourdomainname.co.uk
DocumentRoot /www/vhtdocs/yourdomainname
AddType application/x-httpd-php .html
</VirtualHost>
Then you can use .html files with PHP in either way
Dave