Hi @pc001,
I’m not sure of your business model, but i was wondering if all your listings are going to be in london, why do you need the address search box? I can’t see a use case where a user will be looking for a property at a very specific address. But i can see the case where the user wants to search for listings in some particular area/suburb of london. I don’t know how london is sub divided but if there is something like that, maybe you can have that information as part of the field when creating a new listing. Then users can search with that field.
Or what about doing something similar to what airbnb does (see snapshot below). That is showing a map with pins on the listing so that users can select a listing from the map or from your repeating group.
In case you decide to implement the second option, see the this thread Image in Google Map Marker and Making it Clickable? - #4 by NigelG