Get a good, well-researched introductory book (I recommend Pig Keeping by Richard Lutwyche). The internet is full of misleading and just plain incorrect information. Are your children aware that a mature Vietnamese Pot-Bellied pig can weigh 70+ kg? The smell of pig muck may depend on what they're fed (and don't forget that any food that has been in a kitchen of any kind may not be fed to pigs). You will need a holding number, a herd number and to nominate a large animal vet, as well as keep a herd record and veterinary record. You will also be liable to inspection by Trading Standards, DEFRA and pretty well anyone else who may wish to turn up with zero notice.