I had my twins at Queen Charlottes so not direct experience but three close friends had c-sections there for their twins over the last three years (it's pretty much on my doorstep so all my friends have had their babies there).
All agree that the level of care antenatally and at point of delivery was excellent - good surgery, excellent theatre staff, etc. They all agree however that the care isn't great afterwards as the patient/midwife ratio is strained and they're very busy. All of them felt overlooked and struggled to get help with breastfeeding and help with movement post-section. Given this I think it helps to go in with the mindset that you might not have as much help as you need post-section and plan accordingly. Assume you're not going to get much help without pushing for it and so make sure you use your buzzer as and when you need help with anything (feeding/loo trips/getting out of bed). You might have to keep pressing it before someone comes to you so don't be polite. You may come across as bolshy and annoying but it's better to get help than be the polite lady in the bed who gets ignored. Equally, line up lots of visits from husband/mother so that they can help you. Post section can be quite painful and debilitating and it can be hard picking up a newborn and getting the hang of breastfeeding. Equally, don't chase the pain and be polite about your painkillers. Everyone reacts to a c section differently but the majority of them hurt like all major abdominal surgery does (and should do). They'll give you painkillers every four hours but you might need stronger ones so SAY and ASK if the ones they are giving you aren't helping. I took a morphine-based painkiller called Tramadol which really helped (I had a very brutal emergency section and was very bruised and pulled about) as the paracetamol they gave me wasn't touching the sides. I also had the voltarol suppositories which were great as they worked really quickly. Don't chase the pain as it's harder to get rid of that way. Always try and be one step ahead - I'd start asking for my painkillers after 3 1/2 hours and I usually got them within the four-hour timeframe. The times I didn't it hurt and it took a while to get ahead of the pain again, which made caring for my babies really hard work.
As for kit, take a couple of pillows from home and a couple of dark towels. The pillows are great for breastfeeding as the hospital ones aren't up to much and the more bolstering you have the better. You can protect your tummy and raise the baby at the same time which really helps. Take flip flops for loo trips and the shower (you might not get a shower that has been cleaned since the last person used it and post birth showers can be MESSY from all the lochia!). Take those loo roll wet wipes (Andrex do packs of them) as these are a Godsend for post-birth loo trips as they clean you up (all that lochia again) quickly and effectively. All my girlfriends also too some Dettol wipes to quickly clean loos and baths/showers and although you shouldn't have to do it, the fact remains that the loos can sometimes be a bit grotty because of the shared bathroom/lochia combination. Take earplugs because the wards can be noisy at night.
If you're not getting the help you need then push for it. The ward will be very busy and the midwives are professional and caring but will be stretched to the limit by understaffing (I think every London maternity unit is the same) and so if you don't push you won't get help. Nag about breastfeeding - if you're struggling ask for help and ask if they have any clinics in the hospital or any breastfeeding counsellors who can visit you. Often these things exist but you don't get told about them and it can make such a difference.
Final top tip is a general one. Stand tall!! A friend told me this before I had my section and although all I wanted to do was hunch over my shredded tummy muscles like an old lady, standing tall really helped. And move about slowly as soon as you can, even if it's just for little loo trips. Getting the blood flowing aids recovery.
C&W is a good hospital and their medical care is excellent. The only issue for friends was in the postnatal care and I don't think C&W is unusual in this as it's a problem throughout the UK maternity services. IF you go to hospital with the mindset that it might be a bit hit and miss afterwards and you might have to be a bit pushy with your buzzer and asking for help then I think you'll have a positive experience.
Good luck and I hope it goes really well.