Your credit rating will be shot for six years from the start of the IVA and you can carry on with a business.
If you've not already taken advice then speak to a couple of companies. Vincent Bond (details under the ask experts a question link on the left hand side of the page) can be contacted for some free advice.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
As Kallis says, your credit rating will be shot for 6 years, or until you finish the IVA if that is later (that is when your certificate of completion is issued, which can be up to 6 months after the last payment).
You can carry on a business but might find it difficult to get insurance and a business bank account, if you require one. You will also have to trade on a cash only basis with your suppliers.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014