According to this article https://www.androidcentral.com/how-much-data-does-streaming-... Netflix 4k is 7.2gb an hour, if you have a 1TB Comcast cap and they're counting that as 1000gb you should be fine for at east 130 hours (giving an allowance for phone/app/os updates and random browsing).
Also, why 4k? Small room, massive display? Many people can not even detect a difference between 1080p and 4k at normal couch distance. https://www.experienceuhd.com/blog/can-human-eye-see-differe...