Staying near Wicken for the Easter weekend as we fancy going to the nature reserve there. Me, 13yo dd and the dog. We'd be ok leaving the dog for a couple of hours in the car (weather depending) but can't go anywhere which would mean leaving him all day.
Stuff we like, nice places to go for a walk, nature type stuff, animal stuff, nice towns to have a mooch round (can take it turns holding the dog outside shops), dd likes big garden centres,
. I'm less keen on garden centres. 
Maybe some national trust places??? Dd's not keen on museums, so would have to be something very good.