This might be a complete wild goose chase and probably is... but I was in Tesco in Beeston today and they have Wii U games advertised at crazy prices!
However they have none in stock and when I asked they had no idea if anymore would come in. However I was told this is a national price point for the games as they want to sell them all off before the release of the Nintendo Switch.
Mario Kart 8 - £14-00
Mario Tennis - £12-00
Captain Toad - £10-00
Yoshi Wooly World - £11-00
Mario Party 10 - £10-00
Would definitely say it's worth looking and asking in your local store if you're already going but probably not worth a trip otherwise (maybe you could call?). Anyway hope it helps someone. :D