To put some numbers on this, Stella Artois is 4.8%, so a 568 ml can contains 27.264 ml of alcohol, or 2.7264 units. A minimum price of 50p a unit establishes a minimum price of £1.3632 per can, or £5.4528 per four-pack. Tesco currently sells four-packs in England for £5.50:
https://www.tesco.com/groceries/en-GB/products/250317180