Well, assuming that the death occurred after January 1, 1998. the rate of Inheritance tax varies between 5% and 20% - depending on the total value of the estate of the deceased person.
The real problem occurs if none of the IHT has been paid ... I suspect that you could end up having to ensure that the tax is paid on the full estate before you can register your title. Also, if it is more than six months since the death, there will almost certainly be a penalty to pay as well.
Who was your attorney? They should have checked all these details before the deal was done. I think I recall postings about the right of way to access to your land - which is given by law in any land purchase, so I suspect that the legal advice you received was not good.
