No choice last time I did it; but I've stopped booking veggie special meals when travelling club, partly so I get a choice (and can choose fish dishes if available) but also because the veggie/fishie items on the menu are usually much better than the pre-ordered special meal and there are nearly always decent options.

As an aside, when I've pre-booked a veggie meal in First I've had shame-faced crew nab me the veggie option from CW rather than offer up the meal that had been loaded, which they considered too atrocious for public display.