Will using cellular data use up my credit?

I'm getting an iPhone 5 quite soon on pay as you go and don't want to waste credit. If I turn off cellular data then will my credit be only used for calls and texts? I'm happy with using just Wi-Fi.

This is the correct way of doing it.

Yes that would work out fine, my father in law does the exact same thing since he prefers to use pay as you go and doesn't want to use the internet outside of the house.

You can get some bundle deals on pay as you go though that give you a certain allowance when you top up and some are good value, if you live in the uk you might want to look at giffgaff, a £10 goodybag will get you 500 minutes, unlimited texts and 1gb data, you will never go over because if it runs out it just stops working and it is just like pay as you go because you don't need to set up a direct debit if you don't want to, you can buy a voucher and top your account up each month and it is not a contract so if you can't top up one month it won't matter.