The posts so far is right, although I totally understand the information you seek is elusive. I spent about a month looking at posts about IVA's starting with my mortgage is...
From what I've been able to gather the issues are as follows. A lot of estate agents these days charge (IMO) extortionate admin fees to do a credit check (this costs them £15-30). In my are a the amount seems to be around £200
However from the paperwork I had most state the credit check is only a problem if it shows adverse information which you didn't declare on the application form. If you do declare it I believe they'd want a guarantor or a larger deposit or rent amount up front.
Private landlords are much less likely to do credit checks and shaft (whoops meant to put charge!) you for admin fees.
I have heard of people on IVA's passing the credit check, and I have heard of people having to get a letter from the IP to state they are up to date with the payments.
The main thing from the landlords point of veiw is if you are going to pay the rent. A reference from the current landlord is a must.
Good luck and hope this info helps, god knows it took some finding!