Ooooh, this would do my head in. You go to bed to sleep, not watch telly. You need to lay ground rules down now OP, otherwise the relationship isn't going to go well. And he insists too. Sounds a bit bossy tbh. It's your house isn't it? 
We have a telly in the bedroom btw, but we don't watch it often. It's an old 21" one that we had in the last decade, and it's useful on the rare occasional that one of us wants to watch something different, and there are already 2 things recording on the skybox. Yeah we watch too much telly. 
And also, me or DH put it on when we're cleaning the bedroom. It's not on that often though, and never after we have gone to bed to sleep!
I think if you are together long-term, you will need separate rooms, but as someone said earlier in the thread, don't let him have it all his own way now. If you don't put your foot down with people (whoever it is; husband, in laws, mother, offspring, friend, anyone;) they will walk all over you and leave you angry and resentful.
I'm not going to bash your DP, or say LTB, or he is a child or anything, as he probably can't help the way he is, but that doesn't mean you should have to suffer because of it.