You have a lot to learn about punting, OP
I assume you'll have the horn because you'll have been indulging in certain chemicals. Yes I'm making assumptions but this is Bristol we're talking about...
You will be very hard pressed to find a good service provider who will be willing to see you that late at night AND in a non-sober state.
As you say you are staying in a hotel, wouldn't it make more sense to schedule the punt before your night out?
