If you die without a Will, the distribution of your estate (your personal possessions, money and property) will be dealt with under the rules of intestacy (a set of legal rules which dictate who will benefit). The intestacy rules are rigid and may not reflect your wishes, for example, they make no provision for unmarried partners. The intestacy rules also govern who is entitled to deal with the administration of your estate.
Making a Will is the only way to ensure your estate passes to your chosen beneficiaries. It also enables you to choose your executors, appoint guardians for young children, include cash gifts or gifts of specific items, and detail your funeral wishes. It may be appropriate to include a trust structure in your Will to offer a degree of protection for your chosen beneficiaries or to allow flexibility for future generations to use the trusts for their own wealth/tax planning.