Executor wishing to buy out beneficiary

[Jaylo1]

My brother is the sole executor of my mother's will for which we already have received probate. My mother passed away in February 2017 and I have now been advised that my brother wishes to buy me out as he wishes to develop the house. The proceeds of the estate are split 50:50. I have been advised by his solicitor that they will not give me an indication of when I will receive the monies until I agree a price. They have also indicated that the tax liability might be spread over a period of 8 years and I would like to know if this is allowed.