Prepare for a vet visit

I'm going to the vet tomorrow with my beardo (I suspect she ate something she shouldn't and I'm worried), but since it's so cold outside I'm not sure how I should get her there. I was thinking that I would put some water bottles with hot water that hold heat and shi and put a towel over that so she doesn't get burnt, but the bottles don't fit in the carrier, how do you guys get your beardos to the vet when it's cold?