Argh, I think in your situation, I would take a tour of the Portland and/or speak to a consultant who practises there about your individual situation. That will either reassure you that the Portland is equipped for your needs, and you can add it to your list of possible hospitals, or it won't, and you can discount it. But my advice would be to make a decision based on facts, not on second-hand "horror stories".
You can get quite a lot of information about their facilities from the Portland website (e.g. maternal deaths in 2012 = 0, transfers out = 0, and they have a NICU and SCBU for babies from 30 weeks, and a HDU for mothers.). But I would go and find out for yourself, it really is the only way to get reassurance.
FWIW, I had an ELCS at the Portland last year and had a great experience. The midwives were very attentive, I had pain relief on tap, my husband stayed with me for five days (and was made quite a fuss of because it seems they don't get that many involved fathers there), the nursery staff showed my husband how to bathe our son and change his nappy (we were clueless first-timers), there are great lactation consultants and post-natal physios there to help if you want, and during my CS I had a large potential blood loss resulting from my funny uterus and it was dealt wit so calmly and matter of factly by the surgeon (Mr Pat O'Brien) I had no idea that anything was amiss.