I am so sorry about your back problems. It really is excruciatingly painful and leaves your feeling very vulnerable and frightened.
I had an aggravated disc nearly 2 years ago and I visited a physiotherapist in Balham (Thurleigh Practice) who was recommended to me by a mum at the school gate who had had surgery for a herniated disc. The physiotherapist, apart from manipulation during the sessions also gave Pilates exercises to do at home which were excellent. A lot of back extension exercises, not flexing forward and also stretching the hamstrings. Weirdly this happened during me studying to become a Pilates teacher, having never knowingly experienced back issues or pain before! The irony of it! I remember being in tears because I couldn't sit on a chair during a physiotherapy lecture and feeling sick because we were learning about the spine in detail. I recovered very quickly thanks to 5 sessions:
I now feel stronger than ever and really have felt in tune with my body since experiencing this and know which exercises to do to strengthen my core ( by core we mean back as well) and the weaknesses around the Body which lead to back problems.
As someone who is about to qualify I would say be really choosy about the Pilates teacher who comes to you. I am teaching privately to friends for free but your case is not something I would do without having taken special training in dealing with herniated and slipped discs even when I qualify.
I recommend contacting the Body Control Pilates office near the British museum where I've been training and they have many teachers who work with the NHS. They have a huge database of experienced and highly qualified teachers who will be specially trained and should be able to assist you with a local one.
http://www.bodycontrolpilates.com/shop/ ... finder.php
or you could email them for advice on how to find a teacher. They also have a class called Back 4 Good for those with lower back issues at the centre near the museum.
There are some Pilates teachers out there who have taken a course that takes a short time to qualify and there will be people who shouldn't really be teaching other than those who are fit. Be very choosy and also work with a physiotherapist. The one I recommended is fantastic.
I also recommend Physio 4 Life in Putney where I first fell in love with Pilates 9 years ago, although the prices for classes are quite a lot higher than when I used to go, but they are in small groups now or even 1:1.
There is a lot that can be done to improve your back health.
Best of luck