By the way does anyone know of a validation tool that will handle php & html combinations?
What would be the purpose of that? The W3C validator validates rendered web pages, which will never contain php. The point is to make sure that a standards-conformant UserAgent (such as, I dunno, some browser or another but not some others ) will render your page in a way that conforms to the spec, which should mean, more or less, the same for everyone, blah blah. (I'm not sure how much we trust it, but I don't think it's quite as difficult these days as it was 10 years ago unless the PHB insists that you continue to support IE < 9, etc., etc.)
As far as PHP --- most of us validate PHP by running it and checking for errors. There's an entire book's worth of talk about that. What does your setup look like? I suppose I could understand this question better if you have only one server, the production/WWW box, write your code in Notepad/Pico/Kate/Vim and then put it up on the only server via FTP or some similar technology ... such that you can't test until it's live on the site.
If that's the case, fix this situation ASAP or find another place to work if at all possible ... we want you to live a long & happy life ;-) (I have one site without a proper sandbox and it's absolutely killing me ...)
If you want to "validate" PHP in some other way, you should get an IDE with a syntax checker (most all of them have one, and you should be using one whenever possible & sensible anyway), or run "php -l foo.php" in a command-line context (with a properly configured php cli, of course). If that's too much work, there are online resources that do the same thing, such as http://www.meandeviation.com/tutorials/learnphp/php-syntax-check/v5-3/syntax-check.php (for v5.3).
If you're brave, generally positive-thinking and don't invest too much of your self-worth in your code, you should also check out PHP Mess Detector (https://phpmd.org/).