There are a number of reasons why you and your partner might decide to sell the home: you might need to release funds to enable each of you to buy somewhere else; the mortgage and running costs might be unaffordable for one of you alone; or you might both prefer to move to somewhere new. Whatever the reason, completing a sale is likely to take a while and it is important that you carefully consider what is going to happen until the home is sold. You will need to think about where both of you and any children will live and who will pay the mortgage and other expenses (such as fuel bills and council tax) until the property is sold.
Bear in mind that unmarried couples are not obliged to support each other financially after separation (other than support for any children), so if you are not a legal owner and aren't married, your partner does not have to consult you about selling the property and it is unlikely that you will receive anything from the sale proceeds. (See Different types of ownership). The exception to this is if you have children and the parent with main day to day care needs to stay in the home to provide a roof over the children's heads (see If you have children – when to use a court).
To help you decide whether or not to sell the property, you may like to have it valued to give you an idea of what will be left after any mortgage has been repaid and estate agent's and legal costs of sale have been paid. It is usually best to agree to do this with your partner first (if they also have an interest in the property) so that you can both be comfortable with any valuation that you receive. When house prices are volatile, you may need to get repeat valuations - say, every six months or perhaps more often.
It is also important to bear in mind that the proceeds of sale will be less than the selling price: you will have to pay off any mortgage or other debts secured against the property, and the selling costs.
If the property is jointly owned you will need to agree how you will divide the proceeds of the sale between you. Bear in mind that the proceeds of sale will be less than the selling price since you will have to pay off any mortgage and other debts secured against the property, and the selling costs. If you go to court, a judge will ultimately decide how to divide the sale proceeds, but you could simply agree this between yourselves.
It may be difficult to sell the property. If you have a mortgage, you may find that the value of your home is less than the amount you owe (called negative equity) and there would be no money to divide after a sale. If so, you would need to agree how much each person will contribute to the shortfall or you may need to consider other options. For example, could one of you afford to stay in the property and the other person rent or could you manage to live separately under the same roof, at least for the time being?

Sarah