//if he dies before you, I would have thought joint property would automatically go to you.//
Only if the property is owned as "joint tenants". In that case neither partner owns a discreet half of the property - it is entirely owned by the partnership. If one of the partners dies the survivor assumes full ownership of the partnership's assets.
If the property is owned as "tenants-in-common" each partner owns a discreet half. In the event that one dies that half may be left by means of a will to whoever the deceased partner chooses or, in the event of that partner dying intestate, becomes part of the estate that will be distributed according to the rules of intestacy.