Yes, whoever named those rats has something to answer for! I don’t know much about rats, but if memory serves me right (from school days, so maybe not!), rattus rattus – the black – rat was here first but then rattus norvegicus – the brown rat – came along (on ships) and became more common.
Sorry I don’t have any experience re. lavender – hogs do have a strong sense of smell, but that doesn’t necessarily mean they’d mind, or even that all would. It might be a case of trial and error – maybe start with a low strength and gradually increase to see if they object to it. As long as there are other food sources with no lavender, hopefully they wouldn’t be put off visiting at all. But also don’t know whether it reliably keeps rats away. If you do try it, let us know how you get on.