I’d just offer to keep it tidy over winter, your sheep will take out all the old grass growth and improve it for hay the next year. We have free winter keep that turned into all year round keep, but that’s off the back of the sheep doing the ground good, me moving them when asked and checking regularly. They supply water, I fence the fields. And we always make sure their freezer is well stocked with lamb, and from this year going forward, beef too.
If you can’t afford the rent, and are only putting 15 sheep up there which are basically going to cost £20 each to keep over winter in rent, either cut back, offer to graze it for nothing, or find somewhere else?