Custody advice

JUST wanted some opinions as I am super stressed and worried. I'm in the U.K and me and my babies father were only together a few weeks when I got pregnant I'm 18 weeks today. We have split up when I was around 5 weeks pregnant and he has expressed no interest in my pregnancy he doesn't come to appointments and he says the baby isn't his so I've stopped trying to keep him involved by keeping him up to date with the pregnancy and tonight I got a message saying I'm unfit to be a mother and he will be going for full custody once the baby is born and I'm so scared and worried that my baby is going to get taken from me