I am not allowed to recommend a specific practitioner, but, hopefully others will come along with their suggestions.
I would, however, suggest a small / medium sized firm, rather than the IVA factories, but, it could be that the 'factories' will suit you. You need to speak to a few to see who you feel you can work with over 5 or 6 years.
A read around the forum will throw up names and experiences.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014