I have probably just incurred a late fee (again) on the credit card, so I think I really will set up the direct debit for the minimum payment so it doesn't happen again. I generally pay off in full every month, but from time to time I leave it too late. 
So, if I pay in full a few days before the deadline, does that mean that when the deadline comes round they won't take a direct debit payment because by then the balance will be £0?