I got it on Amazon. Here's one (though I prefer the berry flavor over peppermint):

Gaviscon Max Peppermint Tablet, 50 Count https://www.amazon.com/dp/B01N40O7G1/ref=cm_sw_r_apan_glt_fabc_VNQQDD43SAJMSFX9SCZG

However now I use this liquid, works better for me and tastes good:

Reflux Gourmet - All-Natural Acid Reflux Therapy, Provides Reflux Relief - Natural Supplement for GERD, LPR, Heartburn Relief, Considered Safe for Children and Pregnant Women- Vanilla Caramel Rescue https://www.amazon.com/dp/B086ZYPWQK/ref=cm_sw_r_apan_glt_fabc_J8MZ620STRSBKWMP5V6Y?_encoding=UTF8&psc=1