Thank you everyone, they are fine. I think they just slept through the night and I returned them to their hutch in the afternoon when it had warmed up a bit so that the temperature change wasn't too much.
However, Ringo went a bit crazy when he got back in the hutch and scared the life out of me by jumping over the divide in the top half and falling down the ramp! I was so worried that he was hurt! I picked him up and checked him over and he was the same as always, as soon as I put him back down he was running again so luckily he must have landed in a way that didn't hurt him. I kept checking on him all day, I've been so worried, but he's just the same as always and he ate all his veggies so I think he was just very, very lucky.
I will give them more root veg and maybe get a bigger carrier/crate for when they need to come inside. They get oats on their dry food when it's cold and they love them. Xx