Even with the IVA paid in a lump sum it will still sit on your credit files for 6 years from the start, limiting the lenders that will assist, however, being marked completed will help a little --- but you are going to need a large deposit. Buy to rent might make it a little harder.
I would suggest a chat with a whole of market broker with experience in adverse credit applications. We have two who are members of this forum: Ryan and Shaun. Their contact details can be found in their profiles here: