If you looking for stuff to do then Hamleys has stuff on (for free - am guessing they hope you will be pressured in to buying something!) today was Easter bonnet making and then paraded round store with them on with the big bear thing.
And they have a farm visiting - lambs, goat, tortoise, rabbit, chickens and a duck and you can ask questions and pat them.
Also they are doing demonstrations of things for example glitter tattoo things - so you could get a free one on your hand.
Then you can go downstairs to costa afterwards and have a big coffee and cake as a reward for being subjected to that many children and toys! 
if you check out the website it has details of whats on and when