Breaking up is hard enough without the practical arrangements for living, like who gets the house. What rights you might have in relation to getting your ex out of the house depend upon the legal status of your relationship and of the type of home you live in.
If you are living in rented accommodation or council housing, the right to continue living in the property will rest with the individual whose name is on the agreement. If you are married or in a civil partnership, or both your names are on the rental agreement or tenancy, then you both have a right to remain in the house and a court order would be necessary to force one party to leave.
If you jointly own a property that you both live in, the law allows for each of you to continue to live in or utilise the property equally, without permission or leave from the other party. In practical terms, this means that even if your ex moves out, they could rent out rooms of the house to another person. When an owner moves out of the home, they do not relinquish any right to the property in the future. The only way for one party to remain in the property, while the other leaves, is through a financial settlement agreed between both parties. Each owner is considered to have an equal right to the property if it is deeded in both names, irrespective of the contribution made by each party.
If one party owns a property, they retain the right to live in that property and the other party, with reasonable notice, must move out if asked. If the ex does not leave in the reasonable time allowed, you could change the locks and make arrangements to return their property to them. In most cases, owning a property outright is sufficient legally to enforce a party leaving but in some cases, where the other party has made a contribution towards the mortgage, the deposit or renovating a house, it can be said that they have an interest financially in the property, despite not being on the deed.
Complications that may affect basic legal rights in relation to property are marriage, civil partnerships and children. In all complicated situations, legal advice should be sought. Extra advice is also necessary in cases where domestic violence is an issue. Your local Citizens Advice bureau may also be able to offer free help and mediation to resolve ongoing situations for both parties.