They also had a massive room with millions of legos available to build anything you wanted and another room where you could build and program lego robots.

That reminds me. There is a trick that I think Legoland Windsor has missed.

They have an area where the kids can make Lego models from big bins of bricks. That's great, but the kids can't then take the models away with them.

What they should do is let the kids make the models and the sell them to them based on the weight of the Lego used.