When I moved up here, our vet advised against kittens, as kittens spew out huge quantities of toxo and older cats far less.
We were way out in the wilds up there, so the sheep were only likely to meet up with deposits from our own cats.
Further down, as I am now, one is surrounded by farmers many of whom have an actively regenerating farm cat population and/or who bring in new kittens from time to time. However, I understand that the most likely route for infection is through the cats having used the hay as a toilet, so generally one might think kittens from nearby farms would be unlikely to stray so far or toilet on another cat's territory.
If you and Mrs Womble are happier with an older cat, I'm sure the CPL will be very pleased
. If you really wanted kittens, however - there's always vaccinating the ewes to protect them.