Why is f-secure saying my subscription will end in 29 days when I have got talktalk broadband?
I'm also only an F-Secure user (their home solutions).
Sounds that your installation is only as trial-time account. Did you register your TalkTalk F-Secure account (subscription/promo) based on TalkTalk guides?
I think that one option is to contact TalkTalk support about subject. Another option is try to search TalkTalk articles about registering/installing/activating F-Secure solution.
As Ukko has mentioned, it is best to get in touch with Talk Talk support to check on your subscription information.