I generally haven't been able to use my Switch Debit card in shops and bars, jut to withdraw from machines. So have tended to use my Credit card in shops or withdraw the cash from hole in wall. Lazer seems to be the main debit card there.
You can only use it in ATMs not in shops, but you get a better interest rate if you take it out while there. Just take out big amounts at a time though, every time you withdraw you get charged 1.50 from your bank in the UK.