I don't know anyone who has been asked for a copy of their authorisation
I have - but only once and then on arrival at an agricultural show. You may also be asked at markets where Trading standards tend to pop up form time to time. Small risk at abattoir, but don't know anyone who has. So very unlikely, but possible !
I know people who don't have any.
I took the test when it first came out - 27 multiple choice questions you need to get 20, but they are stupidly simple - the average 8 year old from an inner city would pass, no animal knowledge required. Sample question - which is more important - that the trailer signage for your business is clean or that there are no sharp edges inside the trailer.
Smallholders argue they are not an economic activity.
Defra say they are if income exceeds expenditure - see
https://www.gov.uk/government/publications/welfare-of-animals-during-transportfor a detailed description.
BUT one key exemption, quote from the above
In May 2007, we made a decision to exclude from the scope of the Regulation journeys in which an individual animal is transported with its owner/ keeper from the rules set out in the Regulation. This single animal exemption is carried over from the previous legislation and is not reflected in the current EU legislation. However, the European Commission is aware that we have asked local authorities and Animal Health to retain this exemption in practice.
Historically, the exemption has also been taken as applying to journeys where two animals are accompanied by two people, up to a limit of four animals/four people. This was to accommodate those who are transporting carriage horses for driving competitions or shows. We have asked local authorities and Animal Health to continue to apply the exemption in this way.
So 4 animals/4 people is fine !
Having said all that if you are just moving a few pigs around - then unless you break down, and the authorities find 27 pigs crammed in the boot - the chances of anyone who a) knows the law, and b) can be bothered to do you is really really small. But the risk is there !
As Harmony rightly says, if you're just doing a few for yourself, and not selling to family and friends then you could claim a loss making hobby.