YAY John!!! If you call whatever there is local of RSPCA (is that right for scotland?)/shelter/whatever you ought to be able to find some no-kill options for them. Placing them yourself is not so easy with the allergies, unless you guys have friends wanting kittens for their kids for Christmas. So looking for a rescue or talking to your vet to see if they know someone either wanting them or who rescues...
They're safe, warm and fed. Merry Christmas, kitties!