Good luck everything. DS was born in April this year at 31+5 weighing 4lbs 11.5oz - I think the steroid injections did an awful lot to help him, so it's great you have already had those.
Of course it is all a bit of an unknown until she arrives, but if you can, I agree with the suggestion that you ask to visit SCBU and speak to the staff, so you have an idea what to expect. Obviously you will need to recover yourself from the CS, but my main bit of advice would be to get expressing as soon as possible after the birth - in hindsight, I didn't try for the first 24 hours because I was a bit shellshocked, and poor DS really could have done with the colostrum sooner
. If you don't know what to do (I had to guess a bit), ask a MW to show you - they should give you syringes or cups to collect it in.
Hopefully your DD will have the sucking reflex already - I think it develops around 34 weeks. If she is struggling to maintain her temperature, it may be better at first not to overtire her by putting her to the breast all the time - but the SCBU staff will guide you. I hope you will have supportive nurses, but if you need to you can always request to see the hospital's infant feeding coordinator.
DS was in for 2 weeks and 2 days, just needed to gain weight (he reached his birth weight again the day he was discharged), maintain his temperature and establish feeding. He did amazingly when he came out, put on weight like a total champ - he was on the 9th centile for his corrected age when he came home, and at 6mo he was up at the 50th (greedy baby). You should see the HVs' faces when I tell them he has been exclusively breastfed! So it is possible 
You may want to invest in a good electric pump when you get home (especially if DD is still in hospital then) - I have the Ameda Lactaline - or else you can hire a hospital grade pump from the NCT or other places.
There's also a MN premature birth board where you will find an awful lot of people with similar experiences, and might be useful for more support after DD arrives.
Thinking of you 