NowTV doesn't currently offer 5.1 surround sound on their streaming service, if you got an AV reciever you could use on of the 5.1 pseudo codecs but it not the same as true 5.1 surround sound
Here's a NowTV article linked below which mentions that NowTV doesn't currently output 5.1 surround sound.
Yeah, this is incredible! It's 2018!
I tried to find the settings in NowTV to turn on surround sound, and there aren't any!
My Amazon Prime gives me 4k HDR and 5.1 DD surround. As does Netflix.
I might cancel the Film ticket and ask for the money back. I certainly won't get another month's ticket.
And Netflix is the same price, and doesn't try to divide stuff into Films and "Entertainment".
Nor does it count your devices (I assume NowTV still does this?)