You can use the card at any supermarket that accepts Mastercard and use it like a normal card with contactless x
You have to separate your shopping so cows milk, fruit, veg and baby formula can be paid for by the healthy
Start card. I found it easiest to go to a self check out and put through 2 transactions, one for the healthy start card and one for everything else. Some people say they haven’t had any issues using the card to pay for their whole shop but you do run the risk of the card being blocked if you do that. You have to call up and activate it. The healthy start card also enables you to go to your local children centre and get free vitamins for your baby.