Hamleys toy store could be worth a look. Admittedly I was about 12 when I last visited but it still gives me that 'warm fuzzy' feeling just thinking about it!

Edit: There's also Windsor Castle to go and see; "the oldest and largest occupied castle in the world". Personally, I've never been to the castle but it's a very picturesque town with some nice olde worlde shops. It's also not far from Heathrow airport and has a railway station for ease of access.