No it is not the Happy Valley. It was a much smaller place and was almost directly opposite the central set of steps up to the library. The end of present day Carnforth Close more or less aligns with its former position. You could make your way on foot through here to Oxton road.
No, it wasn't The Happy Valley, (that was at the foot of Penrith Street Flats)the Greek Taverna was actually a small group of houses concealed from Borough Rd through a winding entry lane at the rear opening to reveal a cluster of houses that were called "Taylors Villa's" hope this information was helpful. Wizzo!