My ex partner wants dna test,can I stop him seeing my baby till results are through,he saying he may not be the father

Your title says your unborn baby. If the baby is unborn, there's no visitation to stop. If one of you doesn't think he's the father you should get a paternity test when the baby is born. The court won't order visitation, child support, etc. if one of you doesn't believe he's the father- they'd order a paternity test first.