We have a database containing the names of places encountered in the 1891 census. It has a fairly wide coverage of places, but does not contain the smaller ones. You can use it to help locate places, or to find out the film on which the 1891 census records can be found.
We only have data for England, Wales and the Isle of Man. Therefore there will be no match for places in Scotland, and the Channel Islands. The Irish census no longer exists, and so Irish places could not be provided in this database.