I'd be surprised if the server doesn't already support both IMAP and POP3. It's basically the same email server, just listening on a different TCP port number.
Have a look at this page for talktalk email settings:
Email Settings - IMAP & POP3 | TalkTalk Help
It's more on the client side that the difference is apparent, as you have discovered.
Here's a helpful explanation:
Email: What's the Difference Between POP3, IMAP, and Exchange?
SD