Migration of Websites and web applications such as WordPress from the older Odin (cp.irishdomains.com) system to the newer Plesk/LiteSpeed platform, will take place at the same time as DNS migration of the relevant domains for hosting only plans, and at the same time as email migration for customers using both services.
Static (HTML Only) websites will simply be copied across to the relevant folder on the new system, and should function identically in most cases. If the website was being maintained using FTP or an site design application such as Dreeamweaver or CoffeeCup, then the FTP settings within that application may need to be updated before any changes to the site are published. If the site is updated manually, then the built-in file manager application can also be used.
PHP Websites (Bespoke or non-database)
Simple PHP applications will be copied across to the new server, and in if a database is used, it will also be copied across with the connection parameters staying unchanged. After migration, you should double check the operation of the website as the new Plesk/Litespeed system may implement newer versions of PHP and MariaDB/MySQL, although in the majority of cases no changes to the site will be needed. In general, if a site is dependent on very old PHP/MySQL versions, then it is likely to have security issues and should anyway be updated to protect against defacement or leaking of customer/visitor information.