I am surprised that oxford online would only list the written use of speech for a play, and the merriam webster seems to list no written versions at all.
It is very common to use the word speech not just to refer to the spoken words, but also to the written words that will be spoken. There is even a job called speechwriter, and this guy wrote speeches for Obama.
It is a very common use, and I am really surprised that two respectable online dictionaries seem to ignore this use completely.
freedictionary has it listed under 4b, but it is still confusing:
a. A talk or public address.
b. A printed copy of such an address.
It is absolutely common to refer to any written form, whether printed or hand-scribbled on a beermat, as one's speech:
Have you seen my speech? It must be around here somewhere!
I am just fixing some last small details in tomorrow's speech.
Ah, it does appear in the dictionary of dictionaries, the OED has an entry for it :
(III.8.d.) An address or discourse of a more or less formal character delivered to an audience or assembly;an oration; also, the manuscript or printed copy or report of this.