Can you p for 21???????

well i dont have to be 21 i have to be 18 to buy booze and ive just turned 17 but was getting served wen i was 15/16 and sometimes they will serve me for 9litres of wine thennn sometimes they dont. n i think its good at times tbh coz i dont have to sit outside the shop for about an hour waiting for someone to go in