Your first port of call is the document here: http://www.home- repo.org/dos/statdemand.htm.(posted 8239 days ago)You should then read the Do's and Don'ts section or at least those bits of it that apply to people who have already been repossessed. It is in the "Repossession" part of the site.
Insolvency demands move quickly - more quickly than the tactics that the rest of this site deals with - so it is important to familiarise yourself with the forms you will need to fill in and the answers you will give before the demand actually arrives. So I'd advise that make a trip to your local court to get copies of them.
Then start the questioning process that is so heavily detailed in this site.
Lee