Hi, welcome to RootsChat.

The closest is the National Wills Index, but it is not complete, only work in progress.
http://www.nationalwillsindex.com/Before 1858, all English and Welsh wills were proved in ecclesiastical courts. These did not always equate with counties. It would depend on the extent and location of property and estate owned by the deceased as to which court the will would be proved in. If it was wholly within one parish, then the lowest church court would suffice. If it was in several different parishes or archdeaconries or a different diocese, then it would be proved in a much higher church court. The highest court was the Prerogative Court of Canterbury. The wills proved at this court are at TNA in class PROB 11 and the catalogue can be searched online. Wills can be downloaded for a small fee.
Most county record offices now hold the diocesan records and may well list the wills that they hold in an index. Some are searchable online, e.g. Hampshire at
http://calm.hants.gov.uk/DServe/So your task could be quite time consuming

Nell