To take advantage you'll have to buy any laptop, video game, games console, tablet, smart TV, smart home or smart watch, or any audio gear that costs £49 or more. That's great if you're already planning on buying something anyway, but Currys also sells some games so cheaply that it's worth buying them purely for the sake of Spotify.
The cheapest is Killer Instinct on Xbox One, which at £3.97 [SOLD OUT], which is less than the price of one month of Spotify Premium, let alone six. Jump up by a quid and you can get Anthem on either PS4 or Xbox One for £4.97 - probably a better game if you actually intend to play it, and well worth a fiver even without the free Spotify.
Of course, it's not just cheap games, so if there's something you're considering buying anyway this is a great reason to grab it. Even new titles are on good prices right now - the latest Pokémon for just £37, FIFA 20 for £38, or the amazing PS4 exclusive God of War for only a tenner - all of which come with six months of Spotify too.