If you cannot go on your holiday
Under the Package Travel Regulations you have the right to transfer your holiday to someone else such as a family member or friend. A reasonable administration fee is chargeable by the holiday company for this.
You might be able to claim back the cost of the holiday from your travel insurance company. If you are unable to go on the holiday, for example due to bereavement or illness however you are not legally entitled to a refund from the holiday company.