I can't add anything to the advise about who, when or even if you decide to get an IVA. It has pretty much been covered by our learned members above.
But from my personal experience; It will be a struggle to have any sort of social life for the 5 years, you will be made by circumstance to count every penny to justify 'stuff' you buy that isn't absolutely necessary. You will wear the same wardrobe of clothes for much longer, fashion seasons will cease to exist in your life.
You will feel elation that none of the letters dropping through your door are bills or final notices to pay. Everything you accumulate over the 5 years will be yours, not on credit or payment plan, yours.
You will realise that there are places to shop for a bargain that you never noticed or considered before the IVA.
The day your final payment leaves your bank account will be as good a feeling as seeing your first born come into this world (OK almost as good).
You will find that pre IVA you were a dork with money, you had no clue about how to budget properly, borrowing more money to pay for what you had already spent is NOT budgeting. Post IVA you will be the most frugal shopper and will make 'stuff' last longer or repair it. You wont give a diddly squat that the Jones' have just got a new widget, because you will be smug in the fact of knowing they are 1 pay packet from being in the same boat you were 5 years ago as it is a given it was bought with credit.
Post completion certificate and your credit rating being whistle clean;
You will have a high street bank account, that is always in the black, you will have a savings account that is growing month on month, you will have a credit card, a card that you use knowing you can and do pay back in full each pay packet, after all you only NEED it to continue to have a better than average credit score.
An IVA isn't a bed of roses, it isn't a quick fix, it is a lesson in how you were always supposed to manage your income and expenditure.
Mine was trouble free, I had little to complain about and nothing to say my IP or his staff didn't treat me with respect and completely fairly. Not all IVA companies are the same, some treat the 'contract' wording a little too loosely, a little reading on this forum will almost scare you off the prospect.
Whatever your decision, I wish you the best for your future.
Last Payment made 04/12/14. Completion Certificate 25/7/15. IVA company GT. No Issues