If you're trying to access the temporary URL (i.e. example-co-uk.staging.com) you may get an ERR_SSL_UNRECOGNIZED-NAME-ALERT error.
This will be because the temporary URL can't load over SSL (via https://). To allow the temporary URL to resolve you'll need to ensure it loads over http://.
- Check the WordPress site and home URL and make sure it's set to load over http://
- Disable Force HTTPS in the control panel
- Ensure you don't have the Really Simple SSL plugin active, you can disable it to prevent it forcing https://
- Remove any redirects in the .htaccess file.
You may need to try an incognito browser tab after making any corrections to ensure https:// is not cached in your browser.