@Lindy26 I guess there are two main options - although you don't say if it is an entire property you are renting ora room in your own home
If an entire property, you can ask the guests if they wish to bring their own linen and towels (and use the washing machine) as otherwise there is a charge for linen change over.
If you go for the second option you need to agree how frequently linena and towels will be changed and the additional cost for this. You also need to agree whether or not they do the change over or you do it.
My view would be that for long term rentals you say linen/towels changed every two weeks with them doing the change over. I would also suggest that part of the deal is a weekly or fornightly cleaner to keep the place in shape - it would also serve to keep you happy that the place is being looked after