Nintendo has announced that Wii Fit U has suffered another delay at retail in the UK, but it will still be available to download from the eShop.
The delay means that Wii Fit U won't be arriving at retail now until the 13th of December, 2013. The original plan was for it to release on the 6th of December, but if you already have a balance board, you're able to download a trial of the game from Nintendo's eShop right now.
Should you wish to continue the trial, you'll need to sync the game up with a Fit Meter, something which is sold separately. However, this is included, along with the Balance Board, in the full retail version of the game.