How much to charge?

I have a 4 acre field that has about an acre and a half of natural woodland that was planted about 6 year ago. The field has only been grazed twice in the near 10 years I own it. I have it fenced for sheep and it has water on site plumbed to a trough from previous owner. It is quite over grown and I figure it would be suitable for winter grazing for sheep. It is a dry field and has plenty of shelter. I'm thinking of leasing it for sheep only until the end of January and perhaps February considering it's late in the year. I have no experience of leasing out land so I am wondering how much should I charge.... any info would be appreciated.


EDIT: Last time it was grazed was Nov 17 to end of Feb 18, topped it after that and has had nearly 9 mths growth... never had fertilizer on it.. The 2 times I let it be grazed by sheep was for free for a friend of mine who carried out work for me and wouldn't take payment and he was doing me a favour keeping it ate down