So I did a cheeky test last night before starting on the Brick Bank and it seems that raising the modulars a plate higher, extending the pavement and using plates/tiles as a road gives enough of an impression of a curb, so that's what I am going with. It doesn't look as nice as the brick built roads with the modulars raised up even higher or set into a recession but it's cheaper and quite effective - I'll be sure to take some pictures when I'm done.
This does mean, however, that I have to deconstruct the Parisian Restaurant in order to add a layer of light bley plates to the baseplate, but it's quite a nice problem to have
I wish I had enough shelf space to make an entire road but now only have the space to do half of it, up to the white centre markers. But the method I'm using allows for easy expansion in the future. I'll also likely not run out of road parts as I'm using the minifigure stands in place of tiles.
I've also got an idea for a little MOC, sort of like the seasonal dioramas, of an alleyway containing a mysterious blue police box...