Advice on how to sneak alcohol into a wedding?

Got a wedding on Thursday and safe to say the bar is fecking extortionate, £7.50 for a pint £6.50 for bottles of beer or single spirits and mixer.

Gonna fill my hip flask with a nice whisky but are there any other ways to sneak some in on the down low?

My friend is trying to bring a whole bottle of rum but I don’t see that working.