This brings back memories for me of being 18 and trapped in my parents house.
It was hell. I remember saying that I wished I could get run over by a bus and be in a coma until I could escape.
I too had grown up with physical punishments and even though they never hit me at 18 the fear of it was enough to keep me under their control.
They weren't church people so I didn't have that but they did have control over my work, finances and socialising.
People up thread are saying 'just leave' but sometimes that's just not logistically possible.
I don't know about your situation but I had no where to go and no means to get there (very rural).
If you are under threat of violence you can access women's aid, something I didn't realise when I was 18.
Domestic abuse is domestic abuse, it doesn't have to come from a partner.
You do need to get out of this situation but it may take time and planning.
Do you have your own bank account and any cash in it? Can you claim jsa? Get any kind of work?
Find out how much you need for a room in a shared flat and work towards that.
In the meantime play the good daughter. Keep them happy if that's the best way of maintaining a tolerable living situation.
Just keep telling yourself it won't last forever and you will escape soon.