io ho aggiunto intesta al sito vetrina che ho fatto il seguente codice (come segnaposto html):

<!-- Codice per accettazione cookie - Inizio --><script type='text/javascript'>
//<![CDATA[
(function(window) {
   if (!!window.cookieChoices) {
     return window.cookieChoices;
   }
   var document = window.document; 
   var supportsTextContent = 'textContent' in document.body;
   var cookieChoices = (function() {
     var cookieName = 'displayCookieConsent';
     var cookieConsentId = 'cookieChoiceInfo';
     var dismissLinkId = 'cookieChoiceDismiss';
     function _createHeaderElement(cookieText, dismissText, linkText, linkHref) {
       var butterBarStyles = 'position:fixed;width:100%;background-color:#FFFFFF;' +
           'margin:0; left:0; top:0;padding:10px;z-index:1000;text-align:center;';
       var cookieConsentElement = document.createElement('div');
       cookieConsentElement.id = cookieConsentId;
       cookieConsentElement.style.cssText = butterBarStyles;
       cookieConsentElement.appendChild(_createConsentText(cookieText));
       if (!!linkText && !!linkHref) {
         cookieConsentElement.appendChild(_createInformationLink(linkText, linkHref));
       }
       cookieConsentElement.appendChild(_createDismissLink(dismissText));
       return cookieConsentElement;
     }
     function _createDialogElement(cookieText, dismissText, linkText, linkHref) {
       var glassStyle = 'position:fixed;width:100%;height:100%;z-index:999;' +
           'top:0;left:0;opacity:0.5;filter:alpha(opacity=50);' +
           'background-color:#ccc;';
       var dialogStyle = 'z-index:1000;position:fixed;left:50%;top:50%';
       var contentStyle = 'position:relative;left:-50%;margin-top:-25%;' +
           'background-color:#fff;padding:20px;box-shadow:4px 4px 25px #888;';
       var cookieConsentElement = document.createElement('div');
       cookieConsentElement.id = cookieConsentId;
       var glassPanel = document.createElement('div');
       glassPanel.style.cssText = glassStyle;
       var content = document.createElement('div');
       content.style.cssText = contentStyle;
       var dialog = document.createElement('div');
       dialog.style.cssText = dialogStyle;
       var dismissLink = _createDismissLink(dismissText);
       dismissLink.style.display = 'block';
       dismissLink.style.textAlign = 'right';
       dismissLink.style.marginTop = '8px';
       content.appendChild(_createConsentText(cookieText));
       if (!!linkText && !!linkHref) {
         content.appendChild(_createInformationLink(linkText, linkHref));
       }
       content.appendChild(dismissLink);
       dialog.appendChild(content);
       cookieConsentElement.appendChild(glassPanel);
       cookieConsentElement.appendChild(dialog);
       return cookieConsentElement;
     }
     function _setElementText(element, text) {
       if (supportsTextContent) {
         element.textContent = text;
       } else {
         element.innerText = text;
       }
     }
     function _createConsentText(cookieText) {
       var consentText = document.createElement('span');
       _setElementText(consentText, cookieText);
       return consentText;
     }
     function _createDismissLink(dismissText) {
       var dismissLink = document.createElement('a');
       _setElementText(dismissLink, dismissText);
       dismissLink.id = dismissLinkId;
       dismissLink.href = '#';
       dismissLink.style.marginLeft = '24px';
       return dismissLink;
     }
     function _createInformationLink(linkText, linkHref) {
       var infoLink = document.createElement('a');
       _setElementText(infoLink, linkText);
       infoLink.href = linkHref;
       infoLink.target = '_blank';
       infoLink.style.marginLeft = '8px';
       return infoLink;
     }
     function _dismissLinkClick() {
       _saveUserPreference();
       _removeCookieConsent();
       return false;
     }
     function _showCookieConsent(cookieText, dismissText, linkText, linkHref, isDialog) {
       if (_shouldDisplayConsent()) {
         _removeCookieConsent();
         var consentElement = (isDialog) ?
             _createDialogElement(cookieText, dismissText, linkText, linkHref) :
             _createHeaderElement(cookieText, dismissText, linkText, linkHref);
         var fragment = document.createDocumentFragment();
         fragment.appendChild(consentElement);
         document.body.appendChild(fragment.cloneNode(true));
         document.getElementById(dismissLinkId).onclick = _dismissLinkClick;
       }
     }
     function showCookieConsentBar(cookieText, dismissText, linkText, linkHref) {
       _showCookieConsent(cookieText, dismissText, linkText, linkHref, false);
     }
     function showCookieConsentDialog(cookieText, dismissText, linkText, linkHref) {
       _showCookieConsent(cookieText, dismissText, linkText, linkHref, true);
     }
     function _removeCookieConsent() {
       var cookieChoiceElement = document.getElementById(cookieConsentId);
       if (cookieChoiceElement != null) {
         cookieChoiceElement.parentNode.removeChild(cookieChoiceElement);
       }
     }
     function _saveUserPreference() {
       // Durata del cookie di un anno
       var expiryDate = new Date();
       expiryDate.setFullYear(expiryDate.getFullYear() + 1);
       document.cookie = cookieName + '=y; expires=' + expiryDate.toGMTString();
     }
     function _shouldDisplayConsent() {
       // Per mostrare il banner solo in mancanza del cookie
       return !document.cookie.match(new RegExp(cookieName + '=([^;]+)'));
     }
     var exports = {};
     exports.showCookieConsentBar = showCookieConsentBar;
     exports.showCookieConsentDialog = showCookieConsentDialog;
     return exports;
   })();
   window.cookieChoices = cookieChoices;
   return cookieChoices;
})(this);
document.addEventListener('DOMContentLoaded', function(event) {
     cookieChoices.showCookieConsentBar('Questo sito fa uso di cookie. Se continui la navigazione consideriamo che accetti il loro uso.',
         'OK ACCETTO', '+ INFO', 'http://www.iltuosito.it/policy.html');
   });
//]]>
</script>
<!-- Codice per accettazione cookie - Fine -->

l'effetto è questo:

http://www.ilteatroroma.it/

una volta accettato la scritta non compare più per un anno (o se l'utente cancella il cookie). L'utente può anche leggere prima l'informativa

Si va bene

Grazie ragazzi mi siete stati utilissimi problema risolto 

Grazie ragazzi, molto utile. Buon weekend