I would speak to the agent and explain up front. Provide a letter from your current landlord as this is much more important than whether or not you are in an IVA. It is a buyer's market and numerous properties are lying vacate so if he insists on running credit checks and you fail, go elsewhere or use a private landlord who would have no access to credit reference agencies.
It's the letting agent or the landlord who will make the decision based on the information from the credit check so I would speak to the letting agent.
As Michael has pointed out, references will help here so a good reference from your current landlord and also support from your IP should work in your favour.
Kind regards,
Angela Rosler
Insolvency Manager
Helping people with their debt problems for nearly 10 years.
Contact me directly for free, impartial, confidential help and guidance.