Hi OP I'm a will writer and recommend that you write wills including a Life Interest in Possession Trust. This states that, on the first death, that person's share of the home goes into a trust administered by 3 people; usually the surviving spouse plus someone from each side of the family such as a sibling or close friend.
The surviving spouse is able to continue living in the house until they die or remarry, but otherwise nothing changes. When the trust comes to an end because they have married again or have died, the first-to-die's share of the equity goes to the children, so it gives them a good measure of security whilst at the same time, the surviving spouse has the security of the home.
@Mindymomo says that a trust costs thousands, but this type doesn't, I only charge an extra £150 for a life interest in possession trust, and that includes checking the land registry records and, if necessary, severing a joint tenancy so that the trust can take effect.
It's something which I always advise clients in step families, or older clients worried about care home fees to include in their wills, but there are also lots of people in your circumstances who include this type of trust.