The device made its way to UK shores back in March, and is available for the usual retail price of £35 at John Lewis. You'll want to head through Amazon UK, Tesco or Argos where the sale appears to be in effect. Do note that the Tesco website states the product is currently unavailable, while Argos appears to have lost the listing altogether (although the promotional page is still live).
Here's a list of store links for the Amazon Fire TV Stick sale:
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