Getting took to court for a DNA test

Has anyone had any experience in this my son's dad has now popped up wanting a DNA test I'm refusing because he knows full well he's his dad he's just lied to his new gf saying hes not so now he has to play that role should I get in touch with a solicitor ? He does drugs last I heard so deffiently want him doing a drugs test before he is anywhere near my son all this stress he left me 8 weeks pregnant and now he's not the dad can't cope with this absolute narcissistic maniac the stress 🤦