I found this deal while researching what phone to buy next as my contract on Three is now finished.
There was an advert for £39/mo with 30Gb and unlimited minutes/texts and only having to pay £94.99 upfront, but when I clicked the link it turned out to be £23.99 upfront!
The contract seemed too good to be true, but the phone arrived today and it's all legit! I was kind of expecting it to be an error and the order to be cancelled.
The S8 Plus is available on the same site with the same deal for £49/mo I think.