13 Wrotham Road is between Cobham St and Darnley St. It is mainly houses now that are let into flats..... If you go on Google maps it will show you where.... it is opposite Gravesham Civic Centre..... Iris
Dashwood Cottage was in Dashwood Rd, opposite the entrance to Woodlands Park. It was taken over by Gravesend Council, used as 'drawing offices' and 'parks and gardens' office; now demolished and built over.
You can see Dashwood Cottage on the map at https://www.old-maps.co.uk/#/Map/564137/172926/13/100765Change the zoom level as necessary.Stan