Edith Hamilton's classic
Mythology: Timeless Tales of Gods and Heroes is £1.99 in the UK today as part of today's Daily Deal. FWIW, this says it's the 75th anniversary edition, although I'm never quite sure how that sort of thing translates into e-book...
Kindle UK:
https://www.amazon.co.uk/dp/B071S74DXY
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B071S74DXY