Picture posting is enabled for all :)
I have experience with both :(. Initially I mistook bindweed for couch.A good spit down definitely sounds more like bindweed! Bindweed grows deeper than couch, it snaps more easily and it's thicker (up to 5 mm).
not sure what the leaf in the pic is, but I don't remember seeing any bindweed leaves yet (or is it just too early?!?)a lot of the roots are at least 5mm thick, if not more, so whatever it is it's healthy :owill try and take a better photo this weekend.
Can't say I have seen bind weed, it looks like well established couch grass to me.