A shed! Honestly, they only need shelter from the worst of weathers - they will lay anywhere and stay outside if they can.
If it is low roofed make sure there is an easy way for you to clean it out. Mine was difficult - we used a dog kennel, flattened the roof, and hinged it to one side so I could lift it for cleaning. But it was difficult to get that last bit of muck out before putting in fresh bedding. You could use a (cheap, B & Q, B & M, Homebase, etc) garden shed with a shelf half way up to hold spare feeders, drinkers, food etc - easy to get in and out and clean.