Thanks Sculptex for you advise.

I recently Purchased a SSL certificate and my web host company edited my .htaccess file for me, the code they have used looks different to what you have shown. Would you know what the difference is please?

RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]