Hi Adam and welcome to the forum, I'm not sure on figures but do know that if you take a look at www.iva.com you will find a list of companies and some reviews of these. Try and talk to 2 or 3 companies as it will be worth it to get all important impartial free advice, specific to you.
IVA's were originally for self-employed persons I do believe so that part isn't a problem at all. x
IVA final payment left the bank on the 26th January 2013...looking forward to a debt free future.
You can get an IVA if you are self-employed, but the figures should be worked out on your disposable income - ie the money that is left once you have paid all household and general bilss, and not just from your turnover. What level of disposable income do you feel you would be left with each month to offer to creditors.