my husband had a bit of a run in with a dragon midwife after I'd given birth to our first born. She wasn't involved in the delivery, but was on the post natal ward & went around opening everyone's curtains round their bed, saying "we don't have closed curtains in this ward" (when we were all knackered from labour & wanted a bit of privacy when trying to establish breastfeeding without wanting to show the rest of the ward mammoth boobs etc!). Then she had a go at my husband because I couldnt manage my pudding after lunch, so he ate it. She marched up to him and told him he was wasting NHS money eating my pudding, it was meant for me (even though I'd been served it, wasnt going to it so it would have hit the bin anyway).
My husband quickly put her in her place (a few choice comments, re-drawing curtain round the bed). My community midwife told me to complain about her afterwards in writing.
I appreciate that this was only on postnatal & they were slightly trivial things & not labour ward, but once my hubby had 'stood up to her' so to speak, she was alot more friendly to us (perhaps she realised we weren't all a bunch of naughty school children, which was how she was treating us).
As husband, your job is to stand ground for your wife - she won't be in any state to stand up to a dragon midwife when in labour, but you will.... treat her like you would a difficult colleague, if she crosses the line, or does / says something which contradicts your wife's birth plan, request a 2nd opinion or another midwife. Chances are, the other midwives know she's a bit of a cow (our community midwife knew exactly who we were talking about when we mentioned our experience) so will come to your aid.
Sorry for long post, good luck with the labour, I hope its a wonderful experience for you both.