Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Assuming your husband runs the farm as a business, is or was the plot of land he needs to sell used in the business on a day to day basis?
I can answer this without a phone call which costs extra. Which would you prefer?
I'm assuming your husband runs the farm as a sole trader. He would have inhetrited the land at its market value when his father died and that will be the cost for CGT purposes.
You husband may qualify for entrepreneurs relief which you can read about here. If he does, he will pay CGT at 10% on £38,900 if the land is sold in 2016/17. The first £11,100 of the gain will be tax free due to the annual CGT exemption. You might refer to the articles here and here which may help in determining the possibility of qualifying for entrepreneurs' relief. If he doesn't qualify for entrepreneurs' relief, then he will pay CGT at 10%, 20% or a combination of the two depending on the level of his income in the tax year the gain is made.
I hope this helps but let me know if you have any further questions.