What does the title say?
What has your solicitor said, assuming it got that far that you instructed one - you mentioned you had 3 potential buyers.
Your neighbour cannot revoke/rescind/terminate a right of way / access unilaterally.
Does it not state on your title that you have a right to use the entranceway/pathway between the two properties?
I have answered your question, reassuring you that your neighbour cannot unilaterally terminate any rights granted. Therefore please can I kindly request that you accept /positive rate my reply otherwise the website will not pay me for answering your question. Many thanks.
Happy to assist further if you have any queries or questions in respect of my answer.