I have some notes from a course i attended. I hope it proves helpful:
You can own a property in 2 ways. The first is according to the Title Deeds and the second is according to your contributions to the property, this is called your "Beneficial Interest".
Unmarried Couples may find it better to own a property as Tenants in Common to avoid the problems of the property passing on their death to their partner or their partner's family and not members of their own family. Entering into a written agreement with
your partner when you buy property
together is not strictly legally binding
but can be a very useful indication of your
intentions about the property if you
separate.
If you own property with your partner then you may need to decide what to do with the property after you separate. You may decide to sell and split the proceeds, or transfer your share to your partner, or buy out your partner's share. You could decide that you do not want to sell the property straight away and you want to stay there until the youngest child reaches 18 or finishes full-time education. You may need help from your partner to pay the mortgage, the court can order your partner to help with the mortgage payments.
Within the context of a divorce or the breakdown of a relationship people often think that their partner cannot claim the house because it is not in joint names. That is not the case - particularly in divorce. Within the context of a divorce a wife, for example, may often successfully make a claim against the matrimonial home even though it is in the sole name of the husband. Whose name is on the title deeds tends to be less important in cases of divorce.
However, in the case of cohabitees whose name is on the title and whether the partners are jointly on the mortgage may be of crucial significance. In the case of cohabitees, whether the property which they occupy is in one partner's sole name or whether it is joint, it is almost always sensible to enter into a written agreement about who is entitled to what when the property is bought or when the partner moves into the property. This avoids any dispute later and it is infinitely easier to get a person to sign an agreement when buying a property or when moving in than it is later when the relationship might have broken down. For cohabitees in particular, such an agreement drafted by a solicitor and properly formalised can avoid costly litigation about the property if the relationship later breaks down.