Zen Cart 301 Redirect – Non Www To Www

I have tried using a 301 redirect using the following code in the htaccess file :

RewriteEngine On
RewriteCond %{HTTP_HOST} ^discoveryelectronics.co.uk [NC]
RewriteRule ^(.*)$ http://www.discoveryelectronics.co.uk/$1 [L,R=301]

The redirect worked in that the non www was redirected to the www.
However, I was not able to create a customer user account or log in to the site as a customer.