What do you want to use the newsgroups for, downloading binaries or participating in discussions? Depending on your primary use makes a bit of a difference with your choice of client.
If you've already picked a client out to use, then simply go to wherever you add the newsgroups server and use the address news.cable.ntlworld.com - you don't need a username or password.
Sorry if that's a bit vague... it's late (well, early) and I'm knackered! Let me know if you need more detailed info and I'll post when I'm a bit more awake
Edit: Oh - and port 119 if it asks (which should be the default for newsgroup servers anyway).
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