I bought a bike back off the insurance company a few years ago for the grand total of £50,
i probably sold the parts on for about that much but there were one or two bits on it that I wanted, turned out the whole thing but the frame, fork and wheels was scrap so not actually worth all the hastle but NM
so, in answer of your question you can buy the 'salvage' back off them as it isn't worth their while, if asked why you want it then you think having a bike that is not worth as much and not as attractive to theft might be good for cycling into town / work than your shiny new one (you don't have to stick to that!)
you could probably haggle them to quite a low price for it too.