An old Will refers to the parish's old name eg Wodell - parish finder tells you it is now Odell. Difficult to read handwriting means some letters are obscured - a wildcard search may reveal the missing parish. You know only the dedication of the parish church and the region - a search will reveal possible options. Parish finder has the answer - seven and all were extinct parishes by 1974. Parish finder also has general information about the counties, sees and parishes including how to find the records generated by these bodies.
Most parishes listed include the parish church dedication.
Graham Jaunay's excellent book A Parish Finder for England is available in a new edition now. This book is a wonderful help in finding parishes, and the dedications of each parish.