Eu achei que isso funcionaria, mas isso me leva ao meu site ao vivo
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.mydomain\.co.uk
RewriteCond %{HTTP_HOST} !^127.0.0.1
RewriteRule (.*) http://www.mydomain.co.uk/$1 [R=301,L]
Tags mod-rewrite