Has equity been addressed ? The finish in 3 months might not happen if not as there is the possibility of an extension for 12 months.
In any event it is prudent not to sell until such time as you have your completion certificate. Once you have that you are free do do whatever you wish and keep the proceeds.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014
Once your IVA is completed, the equity (if any) has been dealt with and you have your CC then the IP should remove their caution (if any) from the property and you are free to do what you like with it.
As Foggy has mentioned - has the equity/12 month extension be dealt with? Do you have the standard extension clause in your IVA and do you have more than £5k minimum equitable interest for it to kick in?