Well, this turned out to be easier than I feared when I first read the instructions. I guessed the poet after solving clues for the fifth and sixth letters of the name. Then scanning the poem showed up the remaining solutions.
It’s an error in the form. This has happened before, currently that field will only accept an email address. I suggest give it a day or so and let’s hope they sort it out.
The Guardian really does need to sort these things out. Wrong grid, form will not accept anything other than an email address, late appearance, .... Despite all that, an enjoyable solve.
Good luck with that Prospero, I've already written to the crossword editor twice about a) the late posting and b) the wrong grid but have had neither a reply or any correction made!