When you recieve funds you need to give ur name, sort code, and account no to who ever it is sending the money. they then can put the details in online banking on the phone or at there branch and transfer the amount to you.
As far as im aware, as you can only transfer money thats in your account it happens immediatly. Always has for me so should be secure and you cant do anything with someones sort code or account no anyway. I know some people dont like it though!
hope that answers your question