Not to worry Jamie, I found it!
17) How to move content from WordPress.com to WordPress.org
Looks neat and pretty straightforward.
However, two questions, what if the blog is larger than the maximum amount file size allowed to upload? Is that a case of using the ftp?
Secondly, how about redirecting the existing site.wordpress.com to the new site e.g. domain.com – how do you make sure that the original blog redirects to the new site, hosted elsewhere etc?