Providing you have the necessary permissions to do this, the following in your .htaccess should do the job:
RewriteCond %{HTTP_HOST} !^domain\.co\.uk$ [NC]
RewriteRule ^(.*)$ http://domain.co.uk/$1 [R=301,L]
In place, the full file will probably look something like this:
<IfModule mod_rewrite.c>
RewriteEngine On
# Redirect to non-www domain
RewriteCond %{HTTP_HOST} !^domain\.co\.uk$ [NC]
RewriteRule ^(.*)$ http://domain.co.uk/$1 [R=301,L]
# Send would-be 404 requests to Craft
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/(favicon\.ico|apple-touch-icon.*\.png)$ [NC]
RewriteRule (.+) index.php?p=$1 [QSA,L]
</IfModule>
The following seems to work for me as a generic option:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]
RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ https://%1/$1 [R=301,L]
# Send would-be 404 requests to Craft
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/(favicon\.ico|apple-touch-icon.*\.png)$ [NC]
RewriteRule (.+) index.php?p=$1 [QSA,L]
</IfModule>