Go to the site below and put in your VIN and list the options your car came with and save the file and print out if you can.
http://www.bmwarchive.org/vin/bmw-vin-decoder.html
Now try Liverpool & Victoria and see what the cost is.
http://www.lv.com/contact-us/insurance/car
I pay £283 with fully protected 77.5% discount.