Read up on the LWP::UserAgent's head() method. It will retrieve everything (including metatags) in the target document's header section without retrieving the body.
Comment on Re: LWP: Downloading First 2KB of an HTML File
Meta tags, by definition, are not in the header section (the header section is not the same as the <head> section of the page). The point of meta tags is to include information in the body of the document that really should have been in the header, when you have no way to influence how the web server builds the headers.