There are a few options that you have:

1 - Most leading insurance companies can arrange for a home inspection to assess ya car and make a decision on whether they feel its worth repairing. If they decide its a total loss, they then can organise for a salvage company to remove your car along with your keys, V5 etc

2 - They may want you to visit one of their approved bodyshops for a full estimate to be carried out so that it can be submitted to the engineering dept at your insurer. They then may ask to come back if a engineer wants to see it in the flesh at the bodyshop - as you'll find that most of their shops will have an allocted engineer who will visit 2-3 times a week.

I would be reluctant to do as they ask without a full estimate being done or an engineer coming out to assess the vehicle. I can only presume that they have heard the words 'fire damage' and jumped to conclusions. This is because you have to have a special licence to store extensive fire damaged cars which most decent salvage companies have and your not allowed to keep them on your drive.

Speak to them mate just to make sure they fully understand the damage and what you want.