Hi,
That is pretty. It looks to be a bit later than Edwardian, maybe 1913 to 1914. But I cannot tell much from the photos. It is not a tea dress, although one could certainly wear it to tea I suppose, and some sellers today use that term (although incorrectly in my opinion). As a matter of fact, the term "tea dress" was not a common phrase back then. You might be thinking of "tea gown" which this definitely is not. The fabric, to me, is more of a lace fabric, than a true lace. I know, I am splitting hairs! It has the look of drawn work, but I cannot imagine it is hand done. Hand drawn work would not be done in such a large, all over pattern that just repeats over and over, and the rest of the dress is so very plain and simply made, so pairing it with hand work seems like a mis-match to me. I suspect this was made at home by a thrifty sewer, using machine made fabrics that were purchased at a dry goods store, or cut from another garment. You might call it a lingerie dress (but that might confuse some inexperienced buyers) or call it a garden party dress or lawn party dress. It might also be a graduation dress.
Pretty whatever you decide to call it.