It should be fine.
We have been to Prague three times (2015, 2017 and 2019) and have probably spent on average around 100 euros per day for two of us, excluding our hotel.
Public transportation is extremely cheap, and we found food also very inexpensive. Our hotel included breakfast and we usually only had sandwiches for lunch. We stayed in Vinohrady and ate mostly in neighbourhood restaurants where we spent about 50 euros on dinner for two including a glass of wine.
A lot of Prague can be seen by just walking around. Only things we have paid entrance fees for have been Prague Castle, the excellent Museum of Communism and some art galleries.
can I use EURO , or am I better off buying CKZ before i arrive
We used CZK everywhere but got ours from an ATM once we were in Prague using our Mastercard debit card. We also mostly used credit cards (chip and PIN) for larger transactions like our hotel, restaurants and entrance fees. We needed CZK coins for things like using toilets at train stations.
We didn't see any options to use Euros in our local area. It might be possible at the main tourist sites like Prague Castle but we used our credit card there.
