There are different 0% cards and you need to check, some are mainly 0% BT cards and some are 0% spend cards. I have 0% spend sainsbury and Santander Everyday cards that are 0% spends for the full period (28 months & 31 months)
If you check https://www.nubacards.co.uk/credit-cards/all-round/ it clearly states
0% on balance transfers for up to 30 months
from the date your account is opened (2.73% handling fee). Offer only applies to transfers made within the first 60 days
0% on card purchases for up to 30 months
from the date your account is opened. Offer only applies to card purchases made within the first 60 days..
So whilst it is a long 30 months its only to purchases & transfers made within the first 60 days. Greats if you have one big spend to do,
You need to check before applying as some providers provide more than one type of card