If you are married and have not made a Will, your spouse will not inherit everything, contary to popular belief.
In England and Wales, your spouse will only receive the whole of your estate up to £450,000 free of tax (IHT).
Above that figure, if you do not have children, half will go to your spouse and half to any surviving parents.
If there are no living parents, this half will go to your brothers and sisters or, if they have died, their children.