Insurance for E46 M3

[doyleeoin]

I'd like to insure it as a main car but classic is an option but I can only find company's that say the car has to be over 20 years old.

As Dave stated above, Autoline will quote a 15 year old M3 on a classic policy. Here's the website: https://www.autoline.co.uk/car/classic-vehicle/

I got a quote a few weeks ago for my 2002 M3. It was €730 for 5000 miles a year.