Almost there I think, I created the filr like you said, got the path, put it in, still the same error, so I tried just creating the file in the temp dir and set it to 777, still the same error.
This is how the code looks now.
if(false === FWR_MENU_CACHE_PATH) {
$cachepath = 'home/httpd/vhosts/gamergalaxy.com.au/httpdocs/temp/'; // Tries to create the cache file in shop root
} else $cachepath = constant(FWR_MENU_CACHE_PATH);
P.S. Thanks for all your help, I know im being a pain in the neck.