Merlinfun is the official place to redeem your Kellogg's Grown Ups Go Free offer online.
You will need your 10 digit offer code to hand when redeeming - you can only find this inside special promotional packs of Kellogg's cereal. If you do not have this code, you will need to bring the voucher on the day of your visit to redeem the offer at the gate.
For full terms and conditions, including exclusion dates, please visit here. Please make sure you check opening times to avoid disappointment.