I don't have personal experience of this (though am not a massive fan of hospitals) but have worked with a couple of clients as a doula who've had various issues with hospitals/interventions and or PTSD - so similar situations in which they are worried that childbirth will trigger a pre-existing problem.
Have you thought about a homebirth? This is one of the ways my couples have chosen to handle this, reckoning (correctly it turns out for them) that in their own space, surrounded by their own things and midwives who are more accustomed to hypnobirthing couples/women who want quiet and space etc. she is more likely to feel relaxed and there will be less triggers for panic attacks.
A good site to look at to find out more about homebirth is www.homebirth.org.uk and there are a couple of nice homebirth stories on my website hackneydoula.co.uk/?page_id=26 On the homebirth site you'll find links to local homebirth support groups which are brilliant if you are thinking about it but not sure. Oh and there's a nice support thread on here: www.mumsnet.com/Talk/childbirth/1119378-Is-there-a-home-birth-thread-on-MN
Hypnobirthing/natal hypnotherapy is definitely something to think about. If you can stretch to it I'd recommend going on a course (possibly a private one) so that you are really well versed in teh techniques as is your partner.
It would be worth making sure, as frakyou suggests that you have info on your needs in your notes and on your plan and ask your partner to alert staff to this when he calls midwives out/lets them know you are going in and when you arrive.
I'd really suggest thinking seriously about having a doula (and you can PM me if you like to help you find someone local to you). Trainees charge less than£200 and there is a hardship fund if money is an issue.
I'd suggest finding someone who's happy to do quite a few visits before the birth to really get to know you, understand your needs, help you work through your fears, help you make a really good birth plan that gives you confidence etc. Alot of women find the right doula gives them confidence and belief in themselves that can really help avoid the kind of stress that can set off something like a panic attack. She should also be really good at helping your partner keep a nice protective bubble around you, keep your needs in the forefront of the team's mind and reassure you should plans have to change in any way. www.doula.org.uk has more information.
Lots of women face similar challenges and manage to have really positive experiences - it is totally possible given the right support.