However .. i've just retested it and it doesn't work
I'll find something a bit more useful. The trouble is you need to strip out everything after the the final / for the referrer so it's not the most elegant bit of code.
Try putting this in your .htaccess file
RewriteEngine On RewriteCond %{HTTP_REFERER} !.*suzip.co.uk.* [NC]
RewriteCond %{HTTP_REFERER} !.*suzip.co.uk.* [NC]
RewriteRule /*
http://whereveryouwanttoredirectpeopleto.com/ [R,L]