Hi,
UpdraftPlus has a manual ‘database search and replace’ tool, found in the Advanced Tools tab.
This can be used to change all instances of the URL.
In Search for: food.severnbites.co.uk
In Replace with: http://www.severnbites.com
Please take a backup before running this tool, and be very careful with your input.
If you cannot currently access WP Admin, you can add the following lines to your wp-config.php file:
define('WP_SITEURL', 'https://www.severnbites.com');
define('WP_HOME', WP_SITEURL);
This should give you access.
Best Wishes,
David N