Is it your first offence?
Do you have a clean license?
From what I can remember, you have to be in "charge" of the vehicle to be done for drink driving. i.e. sitting in it with the keys in the ignitition.
Keep to your story (if it's the truth - they'll catch you out if you're lying

) and I can't see what they can do you for? Loitering?!
I got done for drink driving with a level of alcohol in my breath which could've been punished with custody, plus i wrote off the car I was driving, but it was my first offence etc so "just" got banned.
You'll be reet
imo. Unless you're lying or you were a kunt to the police and give them reason to want to see you punished.