Hi Kimberley
Right first things first. Please do not keep them in the house, pigs are farm animals whatever the size and should be kept outside. The dog kennel sounds fine whilst they are small if it is in a pen, but then you need to look at getting an ark for them. I do not think a fox will get them, if you are worried, you can always put a door on the kennel and close it at night, or do you have a stable or something like that you can keep them in. They will also need a good size pen in which to root.
On another note I presume you have a herd number for them and of course the CPH without this you can be fined up to £5,000 by defra.
Lastly and I don't want to be the bearer of bad news, but I would be very wary of these pigs as they grow. I do not know of one micro pig breeder in the uk whose pigs have stayed small. Preloved and the auctions are full of these micro pigs that have started small like yours and ended up as large as some of our traditional breeds. If they are pot bellies crossed with a Kune Kune then you have a chance of them staying a reasonable size, but if they have come from the "founder" in Cumbria then please be very wary. And lastly (again) make sure you only feed them pig nuts and vegetables that have not passed through your kitchen. I would suggest you buy a book on pigs and read up on all the legalities including by law keeping medical records, and that includes making a note everytime you worm them. Good luck and let us know how you get on.