Hello - thought I would just follow up with my experience to answer my own question IYSWIM!
I was admitted to the Carmen Suite, as hoped. It was all much calmer than I remember the medical delivery suite being with my DS (although I think it was probably a quieter day, luck of the draw). We were shown to a delivery suite with a "normal" hospital bed in one corner, but a beanbag, a mattress on the floor, a birthing pool, a birthing stool thing with long lengths of fabric to hold onto above it, and a private bathroom en suite. My NCT teacher tried to suggest it would be more like a spa than a hospital - a bit of an exaggeration, but it was a larger, brighter room with much less technical equipment than I remember the delivery room being.
My main concern was to have a more creative midwife who actually helped me, rather than someone who just took readings and measurements and called in the doctors at a certain point, which I what I had last time. I kind of got this. The midwife looking after me for most of the time was an experienced midwife but new to the Carmen Suite, so I was still examined lying on my back (incredibly painful), she called the doctors when we thought the baby might be stuck and she looked a bit blank when it looked as if I might give birth in the birthing pool. BUT the senior midwife in charge was very experienced and helpful and creative and was there at all the critical moments. She basically used her brain and experience to get my DD out (it turned out she was tangled in the cord, not in a dangerous way but so it was difficult to push her out). The senior midwife suggested changes of position, changes of angle to how I was standing, worked out that my very sticky-outy forwards bump meant that I actually needed to be leaning back a bit, not forwards.
Pain relief wise, I did gas and air and TENs again, fine, but the big revelation was the birthing pool which I got into at the end of the dilation phase - AMAZING - genuinely no pain between contractions. I think this really helped psychologically in having a break from dealing with the pain, which for me is stronger during contractions but basically still there in between, once I'm in established labour.
After DD was born, she was put straight on my chest, uncleaned, unmeasured, and we were left undisturbed for about 2 hours (I think there was an emergency going on somewhere else), which was fantastic. DD fed well immediately during that time and we've had no significant BFing problems since. Then we all got cleaned up and the room was wiped down enough for my family to come and see me in the delivery room itself, so this part of the postnatal care was great. DD was born at 2.30pm in the afternoon and I wasn't moved to the postnatal bed until about 9pm that night - lovely and peaceful.
The Carmen Suite postnatal rooms themselves are exactly the same as the Gwillim ward rooms, 4 beds per room, although there are not so many of them and the corridor outside is lighter, wider and this felt nicer. The disadvantage is that there are delivery rooms alongside the postnatal rooms, so the nights can be very noisy ...
Overall, I did have a better and more positive experience and I would definitely recommend it 