I leave mine to go outside as long as they want, my BT last spring was out in the morning of her due date and then about noon time (I was checking every half hour) was desperate to go inside - kids were born within the hour after that. So they will tell you when they want to go inside (or may be kidding outside if the weather is nice).
If the weather is not too great but dry I also take mine for wee walks just to keep them moving.
Other than that you will need more or less the same as for lambing - something to treat the navel (iodine or Bactakil), arm length gloves in case you need to go in and help the kid(s) out, towels to rub kid dry if nanny is quite tired, and depending on your planned rearing system a lamb bottle for feeding the first feed of colostrum. Also telephone number for vet on your mobile, have a headtorch charged up it will keep your hands free, but start to get the nannies used to them now on late night checks. Keep an eye on the girls eating, if they start to get picky and/or stop eating altogether you need to do the same as for ewes havng pregnancy toxaemia.
I take it the adults had a clostridial booster a couple of weeks ago?
Kids love to sleep in a side-ways open box, a bit like a cave and easily keeps them out of drafts. People used to use tea-chests for that, but I guess not too many of those about any more...I am sure you will find something.
If these are nannies that have kidded before they will probably present you one morning with two litte bundles of joy proudly at their side....