if you think it's hard to pass an assessment before training, then what makes you so confident you will pass it after the training? Willing to bet 100k on it? The assessment actually is harder after training (your 100k lies on you passing that interview, not just a £250 assessment fee), and if your grades aren't 85% above, well the big orange employer will not even look at your CV unless they are desperately short
Fair points in general but lets no exaggerate. If you don't pass the interview after Whitetail training its not a game over, you are welcome to apply anywhere else you want.