Chances are that you wouldn't get classic car insurance due to your age. Mods will go against you as well, try the usal suspects and have a chat with Dave Hollis at the www.britishminiclub.co.uk. He's a great source of info for all things mini related.
Even have a look at the comparison sites, you never know what they'll be doing month to month. Good luck with it though and don't elt em put you off!