You can use your letter as a reference, no problem there.
A guarantor would have to be a person though.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
Hi - the letter of reference will be helpful but a guarantor is somebody who can pay the rent if you default. So it couldn't be your IVA provider. I asked my Dad. Have you found somewhere to rent yet? xx