Below is instructions on how to install Thunderbird and also instructions on how to set up Outlook Express, all you need to do is to open both links and copy the relevant settings from the Outlook Express set up into your Thunderbird email client.
Remember to make a note of your username from your @blueyonder.co.uk account as you will need it for the client to work, it looks like ab001c2345.
Thunderbird setup
Blueyonder set up.