Rocketspark UK sites have a cookie disclaimer embedded in their website that appears for every customer when they come to visit the website. If however, they have set their browser to store cookies it will only show the first time they come to your website and from there it won't show again as they have accepted it already.
You can check the hidden cookie policy page by entering the following into your search bar:yourdomainname.com/cookie-policy/
If you would like to add your own cookie policy and turn off the default cookie policy see the help guide here - How do I add my own Cookie Policy / Banner?