Just for confirmation have you got the smart box identical to the picture below ?
If so and you haven't connected an aerial to it's input socket on the back of the smart box then obviously you won't get any of the Freeview TV channels.
Once you have set up an internet connection on the box you should be able to pause live TV up to about 30 minutes on the NowTV live channels by pressing the pause button on the remote controller when watching any of the NowTV live channels by either accessing from the NowTV EPG or via the NowTV App under Watch Live.
With the internet connected to the NowTV Smart box you will still have access to all the NowTV catch up and boxsets (subject to which NowTV passes that you subscribe too) and be able to use the other Apps on the box.
The only thing that you won't have is the Free Over the Air TV channels because you haven't connected up a TV aerial to the box.
I would suggest adding your vote and if you wish leave a comment on the Ideas board for an improved EPG on your smart box (every vote counts in persuading NowTV to look into this).
Here's the link if you interested adding your weight behind the improvements required on the smart box EPG.
I have just tested the live pause feature on the BBC One HD Freeview channel and was only getting 15 minutes.
Will check the live pause next on the NowTV Sky Atlantic live channel and will report back here later with the time duration that i am getting off my smart box.