Firstly, you need to get advice about whether this is a suitable option for you.
Do you own a property or have a lump sum to 'deal' with?
-If no, then bankruptcy will probably be a better option for you.
Do you have a regular income, which means you can afford to make some payments to creditors? (even if not as much as they may like!)
-If no, then you will probably not be able to enter into an IVA anyway (or seeing it through will not be realsistic).
If you were to make monthly payments at the rate you can afford to creditors, how much of your debt would be cleared in 5 years?
-If all or most of it, then you probably do not need an IVA - a debt management plan may be a better option.
First point of call should be your CAB.
I believe PayPlan and CCCS now both do IVA's, and are probably much better providers than anyone you may see advertising on the side of the motorway! Grant Thornton are another reputable provider.