Unless the burial was in Ramsey you are likely to find it on Brian Lawson's burial list.
www.iomfhs.im/lawsons/burials/cottier_jo.html
- Then compare possible entries with wills for the same or following year, and order those to view through a LDS Family History Centre.
It is unusual for MIs to have survived from the 1700s. Look under (Search) Feltham memorials, in Manx Notebook.

Sue