If you have won the lottery but have not yet received your certificate of completion you should notify your IP who will have full details of your case. While your full and final may have been accepted, the IVA is not officially over until the certifcate has been issued.
Each F&F is individual, you would usually be expected to pay as close to the original dividend as possible.
I have to agree with Michael that until you get that completion letter, the creditors can request money from a windfall and you should inform your IP.
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