To the best of my knowledge, no TV set requires a login to access the internet, per se. However logging in is often required to access certain specific services provided over the internet, such as BBC iPlayer. If you're being asked to log in to BBC iPlayer, or similar, all you should need to do is to enter your account details on the screen. (If you've not already got an account for the relevant service, you can create one using your laptop first).
If that doesn't answer your question, please provide further information about which service it that you're being asked to log in to and why you're having problems doing so.