Wii Fit Released Today
I just reserved mine through and click and collect at my local Argos. I tried a couple of branches and they both had stock, so if you want Wii Fit today, try reserving at Argos.
Also check out Gamestation who are taking orders online. They have it as a bundle, but when you get to the checkout, you can remove the bundled items from the order although I don’t know if they will still accept the order.