Within your account, you can set default region settings, which will be applied to all new titles when they are created. This will dictate on which NetGalley site your books appear (NetGalley.com or NetGalley.co.uk or both) and which regions can request titles.
To do so, click your Company Name at the top of the account (next to the silhouette icon). In the side-bar at the left, look for "Defaults for New Titles" and click the orange arrow next to "Region."
You'll now see the following options:
In this instance, the default is set to list on .com without any region restrictions. To list on .co.uk, simply click the tick next to .co.uk. This would mean all titles created from now on will appear on both NetGalley.co.uk and NetGalley.com.
You can also opt to receive requests only from certain regions. To do so, click the "Set Regions" text. This will allow you restrict requests from any of the UK, EU, Australia, US, or Canada.