If you're on the payroll and get the ticket, there's no harm in having a go. You'll learn a lot, plus you'll have plenty of time to do a proper job.
Just remember, the label is the law when it comes to pest control products. Read carefully and abide by.
Most of the farmyards I know could really benefit from a good tidying,
They're full of features that rats love, piles of tyres, rubble and timber that provide harbourages and drinking water.
If you can find burrows, baiting these direct is a good idea. You can tether your wax blocks to a pegged wire and push it down the hole, or do the same with bagged wheat. Just keep a record of how much you put down and how much you remove at the end of the baiting period.
Shame about the gun ban. Knocking rats down is good sport.