It's ok Being, stop panicking!!! I've found this barn, it accommodates precisely 451 guests. Any more than 451 and it's a fire hazard.
Luckily, the farmer said he's happy to let us have it for the night, as long as one of the guests gives him a blowie. So that's the venue sorted.
We can BBQ the Unicown (with £15 worth of garlic) to feed the guests.