just booked this today - phone 08701 295 041 and quote "sunday mirror offer" and you'll get one free child for each paying adult.
dates advertised as:
27-29/07 Bristol
2/08 Grimsby
4-6/08 Salford
9-12/08 Southampton
15-16/08 Woking
18-19/08 Eastbourne
22-23/08 Southend
26-27/08 Oxford
30-31/08 Cardiff
2-3/09 Reading
ok, you may not want to know that Sarah Jane presents it but seems a worthwhile offer.