Sarah i know 2 mums with gestational diabetes that did exactly this, i think they got about 10mls a day starting at about 37 weeks so that if the baby required milk to increase their blood sugar levels they had it, 1 mum used her milk the other didn't need to. i don't see why you couldn't especially if you are concerned about supply and how you are going to go, even if it is just for reassurance. personally i don't think you will need it AT ALL you will breastfeed your little one with no problems and we will support you through it!
HTH's beckles