I should say so. Some points:

You could use SOAP::Lite module, which act as a wrapper around HTTP and SOAP protocols and can simplify the last part of the script. As I said earlier I personally don't use this module since 2002, so I can't be of much help here

You should use a XML serializer to build the request packet (I myself use XML::Writer) so that it is its responsability ensure the syntactical correctness of the XML stream (tag matching, escaping, an so on)

You said that your service require authentication, but I can't see a header tag in your envelope...