Ethel's wonderfully concise answer basically answers your question but there's an important caveat if you jointly own a house.
If the deeds to the house (or, more importantly, the Land Registry entry) states that you and your husband have a 'tenancy in common', each of you will own a specific share in the house (which is likely to be 50% but doesn't have to be). This share can be left to whomever you choose, in your will.
However, most couples who co-own a house normally have a 'joint tenancy'. When two people hold a joint tenancy (irrespective of whether they're married or not), neither person owns a distinct share in the property, so it's not possible to leave such a share to anyone in a will. When one person dies, the other person automatically becomes the owner of the entire property.
Chris