Definitely recommend this for the over 5's and anyone without a pushchair. Absolutely wonderful day out (we had 2 days). I could not fault it the kids DS 9 and DD 6 loved it.
We did not do Ghosts Alive as it's meant to be very scary.
WC costs £38 for a family of 4 or free if you've got a Tussauds Annual Pass (lots of Tesco vouchers).
I won't tell you all the secrets but you must go. From 11th Dec to Jan they have an ice rink too (bookable separately).
We took a picnic but they have reasonably priced hot and cold food too. Several reasonably priced gift shops too.