If she is in-kid and already in the last 8 weeks you may have to give her more than hay and water, but I would keep it to readigrass or Alpha, oats, sugar beet shreds rather than high protein mix.
Also, don't milk her out, just ease out until udder feels soft, after a couple of days of that move to easing out every 24 hours, then onto 36 hours, two day etc etc... if she goes very full in-between you may have to take it slower. But at this time of year it shouldn't be too difficult, especially if she is not in-kid and therefore does not need any concentrates at all.