In the first instance you must contact the police. You may also be able to apply for a Non Molestation (Injunction) Order.
This is a court application asking the court to order your violent partner from using or threatening violence against you and forbidding him from harassing you. You can also apply for an Occupation Order asking the court to order that the violent partner be removed from your home and not to come within a certain distance of you or your home.
If your partner does not obey with these orders you can apply to the court for his committal to prison.