The guidence I got here in Scotland specifically mentioned hobby breeders and smallholders. Basically it's economic activity if you're running pig-keeping as a business (though it doesn't have to be a profitable one!), but if you're mainly raising a couple of pigs for you and your family it doesn't count, even if you sell some of the pork to friends. I sat the exam: it's 60% common sense and the rest can be learned in half an hour or so. It cost £80 all told, so quite a bit of money, but we do sell most of our pork and are a business so are engaged in economic activity, though not neccessarily a profitable one
The regs say anything up to 8 hours is ok for weaners over 10kg. The longest I've done was about 5 hours (for weaners for breeding) in the back of the car. The car stank, but they were fine!