Colwick Hall
Colwick Hall is located in Nottinghamshire. (Boooooo.)
It's a nice place though, regardless. I haven't been able to visit it, but I have had family look it over for me and they rate it highly. The room I'd hire would be the ballroom. It has interesting decor, a handpainted ceiling (With birdies on!) resting on four pillars and it can hold up to 90 people.
The hire for the room is £1500. Obviously, food is on top of that. And so is everything else. But, generally a good price.