Looking for something for me and my mini

[beakr]

I've been wanting to get into doing some form of motorsport for a while now, but every where I look seems to result in very expensive sport that's also not necessarily suited to a Mini Cooper.

Question is, with a limited budget (£100/mo is absolute top whack), and an open mind, what's out there that I could consider doing? If it's any help, I'm near Horsham in Sussex.