Website Builder now works for the non www. version of your domain name by default, you should not need to make any changes for this to work.
If you find that your Website Builder site is not accessible to visitors who use your domain name without www. in front of it e.g. http://yourdomain.co.uk/ instead of http://www.yourdomain.co.uk/ please raise a support ticket and our support team will set this up for you:
Click on the Ask a question tab in the 123-reg support site.
Type the subject of your question into the box provided.
Select a category for your question, "Website Builder"
Type your domain name into the box provided. This will help us deal with your question faster.
Type your question into the box provided.
Click on the Next Step button.
You will be presented with a selection of support articles that may answer your query, if they do not, please click on the No button. This will submit your query to our support team.