Probably best for you to try the ASDA at The Meadway first before heading all the way over to Lower Earley!
Haven't been there in a while but would assume they have an aisle of toys too.
My boss brings his dog into the office most days and, whilst he's a nice dog, he can get a bit stinky, especially if he's been out for a walk in the rain in the morning (or worse - swimming in a ditch of stagnant water!) Thus any outdoors air is a welcome break!