I have open maps etc installed on my 605 but it lacks the detail required for route planning in detail as a stand alone device,although it shows all roads/names you can’t find most road names bar main roads, so thought garmin’s city navigator will give me what I need, so anyone use it etc and is it worth the £25 odd quid

Which maps are you currently using? Not all OpenStreetMap-based Garmin maps support searching for addresses.
You could try the maps from here, they should work for finding streets: http://garmin.openstreetmap.nl/

On my 705 I have the Topo and City Navigator maps and use Topo for off-road and City Navigator for on-road navigation. Happy enough with the quality/detail of the City Navigator maps myself, bit of a rip-off though I guess.

have tried open maps with search but although they show the names of the smaller roads you can only find the main roads upon searching, will try that link ta