Most hosting companies offer a free SSL through LetsEncrypt, even if they don't offer it automatically you can check out this article https://letsencrypt.org/getting-started/ . Isn't plusnet a broadband provider? I would look for a better hosting company (siteground is very good, free SSL as well). I can't think of any hosting provider who would want you to use their site creator in order to use an SSL, if they do then stay far away.