When entering basics for you account, OMIT entering the password. That usually does it. Thunderbird sometimes gets stuck there. After the account has been confirmed, then enter your password.

Hi David, This got me a step closer. I can now open Thunderbird but it is not receiving emails. I have had the message "login to server imap.talktalk.net failed." Any Suggestions Please

That error usually happens when the server setup isn't correct. You could check with them or post all settings here in hope that someone knows the proper setup for talktalk