Hi BrookeP,
 If you click 'Edit', then go into the 'background settings' layer menu there is a very useful layer in 'Overlays' called 'OSMUK Cadastral Parcels'. This can help you plot individual houses rather then terrace blocks (like i've just done on the Park Lane corner)....or continue with terraces, but eventually they will need to be chopped up by someone.

Happy mapping!

- Jez