It depends on how big your family is and how many activities you plan on taking part in. One Pass may suit you for a short break or you might want a couple for a week long holiday. Remember, should you need them, you can always purchase more Activity Passes once you arrive.
One Prepaid Activity Pass (6 stamp spaces)
£30 in advance - £36 on-park
Two Prepaid Activity Pass (12 stamp spaces)
£54 in advance - £72 on-park