I can't find many listings at the moment but Shop4World has both versions up for sale with Switch at £28.99 and PS4 at £20.99. Here's the PS4 box:
https://www.shop4world.com/nintendo...ungeon-ancestral-edition-ninetndo-switch-game
https://www.shop4world.com/ps4-games/darkest-dungeon-ancestral-edition-ps4-game