Tidy for PHP

I am in the process of going from casual web design to doing it full time.
At the moment I am writing in html but using php includes for my menus and
saving the files as .php extensions.  Is  there either a php version of tidy
or a way of doing includes without php?

I have tried doing it like this and saving the files as html  <!--#include
file="_includes/mainmenu.html" --> the code cleaned up and corrected the one
error (I use Screem) however the include didn't work on my website.

I'm not sure whether this is because my site supports php but not this sort
of include or what else could have happened.
Any advice would be greatfully received.

Susan

-- 
OPC for Lanteglos-by-Fowey
http://www.cornwall-opc.org/Par_new/l_m/lanteglos_fowey.php

OPC coordinator for Wiltshire
http://www.rootsweb.ancestry.com/~engwopcp/

Secretary to the PCC St. Michael's Headingley
http://www.st-michaels-headingley.org.uk/