If the property is only in your partner’s name and you were not married or in a civil partnership, you do not automatically have a financial claim to it just because you lived there or were in a relationship. The usual starting point is that the person named as the owner owns the property, unless you can show that you have a financial share in it.
You may be able to make a claim if there was a clear agreement or shared understanding that you would have a share in the property, and you relied on that agreement in a way that disadvantaged you financially or practically. This type of claim is often based on a “constructive trust”. Useful evidence may include payments towards the deposit or mortgage, significant contributions to renovations, conversations about ownership, or other behaviour showing that both of you intended you to have a share.
If you cannot agree, you can ask the court to decide whether you have a financial share in the property and, if so, how much that share is. This is usually dealt with under the Trusts of Land and Appointment of Trustees Act 1996. However, paying ordinary household bills, contributing to living costs, or making rent-like payments will not automatically give you a share unless those payments are linked to a shared understanding that you would own part of the property.