Do I put my normal bank details?

I can't open a student current account yet because most of them need you to be 18 (which I'm not until August) or evidence of having an accepted place at a uni and I don't have an unconditional offer, so when it asks for my bank details do I just put my current account details at the moment and change them when I can get a student account?

Yup

Depending on which bank you chose for your student account then you might not need to change your SFE details (if you stay with the same bank and provide proof of being a student they will usually change the account type without changing your sort code/account number).

IF you change banks then make sure you get your details correct on your SFE account in August and you'll be fine